I have seen many questions & answers regarding practising sight reading the right way etc. But I couldn't find the answer to my question whether it is even that important to practise sight reading. What I mean by practising sight reading is for example picking a random piece that you haven't played before which is below your level and practise sight reading everyday with random pieces like that. But is it even necessary? Don't you automatically develop your sight reading skills just by working on your pieces at your level, instead of practising sight reading SEPARATELY with random pieces?
Yes it is really important to practise sightreading. Being able to sightread well makes it much quicker to learn new pieces and eventually possible to play pieces reasonably well without having practised them at all.
Sightreading does improve simply by learning repertoire, but not that quickly. This is because you are only truly sightreading a piece the first time play through it. After that, you will have memorised at least some of the material, and are no longer sightreading in the strictest sense.
This is often a problem for pupils studying for instrumental music exams. Once they have memorised their pieces, and are “polishing” them, they are not really reading the sheet music while playing them, even if they are following the music to aid memory. For this reason I find it really important to ensure that pupils read and play a wide variety of new music alongside pieces they may be learning in detail for exams or performances.
Mandatory, as in "commanded"? No, but if you see it that way, you'll resist it.
I'm a guitarist, and you probably know the joke, "How do you get a guitarist to stop playing? Put sheet music in front of him!" Accordingly, I neglected this skill until I was 50, to my detriment. My answer now is not that practicing sight-reading will make you better at...sight-reading. That's obviously true. My answer is that it will make you a better musician. There is almost no other way to compel yourself to work out fingerings for music you would never have imagined, or to connect these fingerings to music theory (i.e. to relate what is obviously an arpeggio in the written music to an arpeggio on the fretboard). You may be a native genius (IIRC Wes Montgomery didn't and George Benson doesn't sight-read); then again, you may not be. If you want some insight into how a Charlie Parker solo, or a Bach cello suite, is put together, get the sheet music and struggle with it.
As you get better at sight-reading, you'll begin to be able to play notes you've already scanned visually, while your eyes are already on the next measure. You will necessary internalize scales, arpeggios, etc. You will necessarily learn to shift positions, which you'd otherwise avoid.
I could have chosen to noodle on the blues scale from now into my golden years, but I realized I was getting bored. There's plenty of interesting music out there...in written form. Learn to read it.
Reading in general, and sight reading specifically may never be used by some players. If you are playing in a band where you are writing all the parts and don't plan to play in another setting then maybe reading isn't going to be on the top of your list of things to practice.
But if you want to be good at sight reading the only way to practice is to read stuff you have never seen before, or haven't played to the point of memorization.
Think of this, when you were first learning how to read (books not music) you had to sound out each word. Once you learn a word well enough you can just look at it and know what it is. Now when you read for the most part you just know most words. However, sometimes you come across a word you have never seen and you will need to sound it out. If you do this enough times you no longer need to sound the word out, you can just see that it is the word. Sight reading is sounding out the words in real time. If you do it enough you learn that word. This is different that memorizing a speech or a poem. It is learning the ability to recognize that word at first glance.
If you ever want to be a studio musician, or sub for an orchestra player, or countless other settings, it will be very beneficial to learn how to sight read.
As far what you say when you say:
practicing sight reading is for example picking a random piece that you haven't played before which is below your level and practice sight reading everyday
This indicates to me that your sight reading level is below your playing level. I think each player may have different levels in different areas. Some players can't read but are great at improvising. Some can sight read very well, but can't improvise. Sounds to me that your sight reading level is below your playing level. If you want to improve your sight reading to catch up to your playing, then you need to practice sight reading. If you are weak in reading in general, sight reading will help with that BUT reading the same piece over and over might not necessarily help your sight reading beyond a very basic point because you have memorized the "works" only in that very setting. To sight read you need to test those words out come at you in a setting you have never seen before.
Hope this helps.
One thing that may not be obvious at first is that you will need to use sight reading skills at random times. You'll sometimes be the only musician in the room and there will be a call to play some hymn, or national anthem, or locally-important-piece-of-music, you will be chosen. I'm not even a professional musician but I've been call upon to do such things as sight read a Gilbert & Sullivan score so the singers could practice (takes to long to describe the circumstances.) Once, my mother had to fill in for a concert pianist who suddenly took ill on the day of a performance. She got to sight read a concerto without the benefit of rehearsal with the orchestra; the bragging rights still linger.
Sight reading only takes practice; it's no worse that learning a piece from memory; it's just a different skill. You will use it.
It is my opinion that sight reading is a byproduct of a knowledge of music theory, having a trained ear that knows where the music is going and a solid technique so you don't have to think about how to play what you are trying to play.
When sight reading, most of us are not seeing EVERY note. Our brains can fill in the gaps when we combine theory and ear training. For instance, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit a porbelm.
So no, you don't need to practice sight reading. It will happen when everything else falls into place.
Although, some people have a fear of making mistakes and are obsessed with reading every note. Those who are a slave to notation never become good sight readers.
You can improve your sight reading by laying by the pool, transcribing music in your head. But, if you are like me, you'll fall asleep in two minutezzzzzzz . . .
Practising sight reading alone isn't that satisfactory in the progress department. Certainly read through stuff below your level of playing, both with just rhythm, l.h. and r.h. and together.
Problem with doing it alone is that you won't know if you're getting it right. With someone to guide you, it's a very different situation.
Mandatory? Who knows? To get full marks in the sight-reading section of exams, of course. To be able to hear something and play it back? No help. To be able, eventually, to play anything in any style, with the dots in front of you? Way too obvious an answer!.
It's up to you. Want to become a fully rounded player and musician? Better buckle down to it. You probably learned to read words so long ago, you can hardly remember doing it. Ask the simple question, do you regret learning how to?
While I can't answer for the piano, I can say that as a classically trained vocalist, the ability to sight-read music is invaluable.
If you talk to any of the members of any professional singing groups around, you'll find that they might not have the most beautiful voice of any of the people who auditioned for their parts, but the ability to sight-read through music got them the job.
If you want to be able to sight-read, it is important to practice it. It is not something that must be done every day, but periodically take out music that looks "readable" and play it. As a pianist, my ability to sight-read has served me extremely well. I work primarily as an accompanist, and my sight-reading ability cuts down on my total practice time a tremendous amount. When I can get 80-100% of the notes correct the first time, it does not take long to polish off a new piece.
I started practicing sight-reading at age 5 or 6 when my piano teacher started randomly pulling out new pieces for me to try which weren't part of my regular practicing for the week. Later on in my teens, I would pull out songs for fun that I just wanted to "try", whether it was some rock-song arrangement or some Mendelssohn. Being able to read new stuff quickly allows you to assess a piece and decide if you like it enough to polish it, even if you don't need the skill for a job like I do. It also means that you don't have to be dependent on others to play it for you (in person or via recording) to get a sense of how it goes.
As has been mentioned above, a knowledge of theory helps tremendously. I do not really read every single note. I see the patterns of chords and intervals and that helps me quickly process what's on the page.
I also would say that sight-reading doesn't do much of anything if you do not know your instrument well enough to find the notes quickly. Scales and chords (block and arpeggio, all inversions.) Over and over and over. Your hands need to be able to feel the patterns automatically when you see them on the page.
Nothing in life is "necessary" except death and taxes. There is a bit of opinion to this. Sight reading has two purposes (both really the same, to be literate).
To learn pieces by reading the score for the piece. For this type of work it is not necessary, expected, or even possible for some musicians to read through a piece first time without mistakes. A concertmaster or soloist could spend a year or more (estimate) working up a set of pieces for performance.
To read on the spot if a job calls for it. If you get called to sub in a pit or similar type of gig you may get a short time to read through the music score. On occasion you may have read through a new piece on the spot (I've been there).
Reading random new pieces is great training for the second scenario. It is absolutely NOT necessary and you are right in your statement that by reading anything you are getting a work out at reading. Some musicians may develop good sight reading habits and skills w/o the type of training you are asking about, but for many this does help. Especially on instruments where there are several options for playing the same voicing of a chord or melodic pattern (like the guitar).
On a completely different note, literally reading music out loud but reciting the letter names is a technique that improves sight reading overall.
Trying to learn to sight-read on the piano as a kid is one of the reasons I no longer enjoy playing the piano. I don't believe you should feel any pressure to learn to sight-read unless you want to. I know it's in exams but I don't care, enjoying what you do when you play piano is far more important.
In my opinion, it's far more fun, social, and useful to learn to improvise than to sight-read. Improvising is rewarding in-the-moment, and to make it sound better when you have no-one else to play with, you can just pick one of millions of backing tracks on YouTube and jam along. It might feel awkward at first if you've never done it before, but eventually it gets really relaxing to do this.
Improvising for long enough will eventually naturally lead to an interest in keyboard harmony. Keyboard harmony is being able to play chords to accompany a melody (either sight-read or improvised) in real time. It is incredibly useful, challenging, and more focused than a vague 'practise sight-reading' instruction.
Knowing keyboard harmony will ironically lead back to knowing how to sight-read in a much more effective way: you'll be able to eventually identify chord structures along a whole bar or even line at a time at a glance. This will mean you don't have to sight-read by going note-by-note (which is like reading language by reading letter-by-letter, you'll never be able to go quick enough). Chords are the words in music and chord sequences are the sentences. It was only after knowing a bit about chords that I ever became marginally less hopeless at sight-reading.
I found it far more rewarding to study harmony, both on paper and at the piano, than I ever did forcing myself to pick up a random piece a day and fail at playing it.