Picture taken from Google Images
I would say no. Getting your fingers conditioned to playing is a necessary step. Unless you have some unique medical necessity, just play a little each day, and when your fingers get tired take a break. After a few weeks will find you will be able to play for longer periods without it feeling like the guitar hates your fingers.
Guessing it's either on your fretting fingers, or plucking fingers. Neither should be necessary. If it's a well set up guitar, and the strings are not too heavy, making them very difficult to press down. there won't be a problem there. Some will say you'll develop callouses - very hard skin - on fingertips. In the last 50 yrs or so, I've never had them. Maybe it's me, and the way the guitars/basses are set up.
If it's for the plucking fingers, again, no, as you use the finger pads and/or the fingernails and anything worn on fingers/thumb will be detrimental. If you want to strum, use a pick. If you want to pick, slip-on finger picks are available.
When you play, and you reach the point when your fingers ache or hurt, it's just God's way of saying 'have a rest'!
This may be more of the same, but here is my 2 cents.
I cannot tell what the purpose of the device is. Ideally you want to develop a haptic connection with your instrument so it becomes an extension of yourself. That being said my first reaction to these devices is that you will NEVER develop the right feeling using these things. But then I am reminded of Tony Iommi of Black Sabbath who lost the ends of two of his fretting hand fingers early in his life in a work related accident. He has prosthetic ends made of wood and leather. So he cannot feel the tip touch the string but over time I would guess that he developed sensitivity of the wood touching the end of whatever skin is touching it. That would evolve into a true haptic connection.
I can only imagine that these little devices "protect" you skin from getting sore when you play. The problem with that is that you need to evolve past that to develop real chops with both hands. If you are using these to allow yourself to play past an amount of time where you would feel your fingers getting bruised then I would say your actions are self defeating. Here is why I think that. Presumably, in time, you will take them off. When you do this you will essentially be starting over and need to develop that haptic connection from scratch. This happens to experienced player if they decide to change technique. The evolution time is usually not as bad as starting over but can take several months is the change is drastic. You are setting yourself up to not learn. If, on the other hand, you intend to uses these forever I see no reason why you cannot develop a good tone and technique but now these pads will need to be part of your playing to get the feel you are used to.
In general I think devices like this are a marketing gimmick and serve no real purpose to beginners. Similar gimmicks that have misleading arguments for use in guitar playing are (1) the spring loaded grip developer, and (2) the guitar with LED lights on the finger board to light up the correct spots to finger in any key or mode. Neither of these helps in the learning process and can have negative effects over time.
Considering that your image is of an ukulele, let me share some of the ukulele playing perspective.
Generally, finger guards on the strumming hand of the ukulele is not really advised. You could, for sure, but I don't think you'll need them. If I may guess, I think that probably after playing a little while, the strings start to feel as though they are cutting your fingers or making them raw. I think that if your fingers start to hurt, the best way to handle it would be to stop and let your fingers heal. Eventually (for me this started to happen within 2 months of starting playing), I stopped feeling any pain. Especially on ukulele, with non-metal strings, finger guards shouldn't be necessary. If you want to use them, you can, but here are a few pros and cons:
- One's fingertips are protected from the pain
- Possibly a better grip on the strings
- Maybe a cleaner tone(?)
- Vibrato and natural harmonics might be easier
- Playing with a slide is impossible
- If you have medical complications from this, the of course this will solve your problem
- Finger guards don't protect the rest of the finger, so barre chords will still be in contact with the skin
- Slides might be affected/harder
- Vibrato might be harder, and the possible benefit of natural harmonics won't apply to artificial harmonics
- Your fingers will effectively be larger, making cramped positions more difficult
- It's an additional cost, as well as they will break over use/time
- People will think you're weird (that's their fault, but still)
- Pull-offs might accidentally pull the entire guard off of your finger
As for guards on the picking hand:
Let me just say that I learned to strum with the nail and skin of my index finger, which did start to hurt when I first started to play. After a few months, though, it stopped being a problem. I'd say if it hurts and you're not bleeding, you just stop playing. If you're bleeding, you're playing too hard or too much or something. That aside, there are other better options, for example thumb strumming or using more than one finger, or of course fingerpicking. Here are some pros and cons of guards on the picking hand:
- Artificial harmonics also get easier
- Less strumming pain
- Better grip on the strings if fingerpicking
- It will allow you to play much more forcefully, as it won't hurt to play louder
- You might even need one on the thumb, because thumbs are a big part of strumming
- One can never vary their tone by using nails, because the nails never touch the strings
- Different tone when strumming
If you start with guards, you're either going to have to eventually learn to play without them, in which case it's better to learn that now, or you'll use guards forever, which might be fine, depending on what you decide. It's your choice, but I can't say that they are necessary, as most ukulele players never use these. Also consider that guitarists and bassists also never usually use these, and they have to deal with metal strings and much thicker strings. String instruments also don't use these, and I can't think of any instrument that does use them.
if your fingers hurt use smaller string size