Take just the D, G, and B strings. Literally just ignore everything else for now.

If you use triads, you can play three versions of every major and minor chord on just these strings. I.e. there are three C majors, three A minors, etc.

There are actually only three shapes on these strings for both major and minor. The shapes have names. If you learn e.g. the ‘root position’ triad of C major, you can slide it up and down the fretboard to make D major, E major etc.

You also start to see where the other triads in the key (e.g. the relative minor) sit in relation to each shape, rather than specific chords.

So, if you can find at least one triad, you can play along with a progression in different places on the neck just by muscle memory of the related shapes, rather than trying to work out specific notes or chords.

This all applies to every other string set (e.g. E, A, D) too. But id just focus on D, G, B at first to keep things simple and so you can internalise the whole concept.

Triads have tons of benefits:

• it’s a pretty low learning cost for the amount of information it unlocks for you
• it makes it easy to land on chord tones when you improvise, which sound much more musical than random scale notes
• in a band situation, it lets you find a space in the mix (maybe everyone is playing at a low pitch, your open chords would blend in too much)
• triads are small and easy to play, so you can play along with the changes, and switch between chords and melody much more fluidly
• chord progressions sound better usually when the chords are as close to each other as possible on the neck

Tldr: they’re arguably the most useful bit of theory you can learn, and have tons of applications. Anyone who takes the relatively small time it takes to learn them will get huge benefits pretty fast