It seems like if I memorized the relative intervals between the notes on each string, it would help a lot with quickly making chords and such. It seems a lot easier than trying to memorize individual notes. Would this be useful, or a waste of time and energy? Also, if I were to switch to an unfamiliar tuning, would I be completely screwed in that regard? I imagine this would also really help my memorization of the notes in relation to each other, i.e. a circle of fiths.
It seems like if I memorized the relative intervals between the notes on each string, it would help a lot with quickly making chords and such. It seems a lot easier than trying to memorize individual notes
Yes, of course! The majority of guitarists have a way to think "directly" in relative terms - often using shapes as mnemonic aid. If you think in terms of numbers of semitones, and have the ability to see shapes on the fretboard in terms of numbers of semitones (and/or intervals like an octave, fifth, etc), then you can easily do all the musical 'operations' you need in your mind without needing to think of note names.
Note that this isn't 'cheating' in any way, or specific to the guitar. It's just as possible on the piano to 'spot' intervals without thinking of the particular note names. It just so happens to be very easy to relate piano keys to note names, due to the octave-repeating pattern of the keys. The guitar doesn't have such a clear pattern (at least, not once you start to move across strings), so it makes less sense to concern yourself with note names when you don't have to.
Of course it is still useful to be able to find named notes on the fretboard, but you don't have to think in terms of them all the time.
if I were to switch to an unfamiliar tuning, would I be completely screwed in that regard?
No more than if you were thinking in terms of note names - those would all move too, if you re-tuned.
One habit to get into is to just work out how a chromatic octave maps to shapes on the fretboard on your particular tuning. Once you've mentally 'mapped' the octave, and once you're thinking in terms of intervals, you should be able to play familiar tunes with only a little extra mental effort compared to standard tuning.
I find this knowledge extremely useful, and somehow required if you want to go past cowboy chords / most common shapes.
You already make use of it when you tune your guitar, if you use the 5th fret method for instance.
If you are playing richer chords, knowing where to locate the root / 3rd / 7th / nth degrees grants you full control on what you are doing. Of course you could rely on existing diagrams, but if you interiorise such notion you are able to explore the fretboard further, and to come up with pattern and strategies that are more comfortable to your playing style.
If your melody phrasing involves slides and bends, of course you want to know the horizontal fretboard landscape, not (just) in terms of the notes you are hitting, but also as interval relationships. This way you never get lost, and you can go back to a vertical approach (i.e. playing across different strings) whenever you want.
- you play an E (5th string, 7th fret), followed by a G (4th string, 5th fret);
- you know those notes to be a minor 3rd apart (i.e. 3 half steps);
- then you can also play the G on the same string 3 frets up -> 10th fret. This way you can hammer on / slide if you need it.
Muscle memory will do the rest.
If you change tuning, your perspective changes a bit. But if you know the relationships between adjacent strings, a bit of practice will suffice. Always remember that you change tuning with a purpose (i.e. to play something in a easier/otherwise impossible way), not just for the sake of it!
In my experience, it's an essential skill for both soloing and chord building.
Most of the time when I'm soloing, I'm visualizing the current chord on the fretboard, and then using my knowledge of interval shapes to make my note selection (e.g. I always know my 9th is two frets above my roots).
When it comes to chord building, I will say that it isn't great for building voicings larger than three notes from the ground up. When I'm writing voice leading stuff in three parts, I definitely think in terms interval shapes. But when you're playing the more standard "guitaristic" voicings (barre chords, 6 string open voicings etc.), it's more efficient just to memorize the shapes. However, interval shapes are a great way to extend those voicings. I can easily decorate a standard minor or major chord with a 6, 9, 11 etc. because I know their positions relative to the root.
On the flip side, I also make voicings sparser by deleting notes with the same technique. It's quite common in jazz to remove the 5th, root, or both from a chord, and I also use interval shapes to figure that out quickly.
And yes, there is an inconsistency due to the B string. For instance, the sixth is two strings up and and one fret back if your root is on E, A, D, but it's two strings up and on the same fret if your root is on the G string. However, this will quickly become second nature in my experience.
Quickly making chords? The way most guitarists do this is to actually learn the shapes - at the very least the basic shapes. Even knowing what the makeup of, say, F♯7♭9 is isn't usually enough, knowing intervals, etc., to finger that chord when it comes along in a song. Unless you're practising.
Yes, it's a good idea to know where certain intervals are found - ane they're always going to be on relative fret positions, which get messed up between G and B strings! So, it's not a bad idea per se, but for being able to instantly make up chords - it won't work. Mainly because chords are made up of more than one interval, and voicings being important, will create a minefield with that mental state.
And, yes, when you switch to another tuning, you'll have to re-learn all the intervals and there locations all over again, just like you'll need to learn new chord shapes, etc.
And, you already have the circle of fourths/fifths. On the bottom four strings at least. So, in a way, that's a given.
Yes it is a good idea to know the relative intervals between notes - it is actually very normal for development as a player. Learning the intervals is necessary to know scale patterns and also form chords on the guitar. You will 'naturally' learn some quickly (e.g. finding thirds or fifths/power chords), but investing time will help you progress faster and further.
The guitar excels as a transposing instrument, and knowing the intervals is a big step in that direction.
Changing tuning will affect this knowledge. In Drop D, it has a relatively small impact since only 1 string changes. The impact is larger if you tune further away from standard (assuming you learned in standard tuning).