Meh, I just memorise everything.
<snip>
The brain is weird.
Yeah, I'd say your brain is weird! So not only do you have absolute pitch, but now eidetic memory as well?
It's OK, you're just a young boy, so your brain hasn't gone smooth yet!
Yeah, I am a bit envious of your memorization abilities: that's pretty much the only thing I'm stuck on, aside from (more than a few!) technical deficiencies.
But, seriously, I do think exploring historical manuscripts, including 20th C editions published by some of the usual suspects is the real reason to use the PDF format. However one might acquire them.
Especially handy for Bach, I find: things like that where each editor has a very personal take on not just the notes themselves, but where to place them on the staves. Helps for sight-reading quickly, I find.
I'd guess the ratio is like six to one or so of editions I scrutinize in digital form, compared to editions I purchase in bound form. I like to have one bound, printed edition of each piece I'm working on, though. And, yes, for something like the Beethoven piano sonatas, I prefer the breakout editions of each opus, in whatever edition one finds. Not so much into the giant volumes that can be awkward to manipulate on the music stand.
It's almost a question of organization at some point, rather than preference, when one has accumulated a bit of a private library of scores.
In addition to the occasional rewrite using some engraving software for study purposes of, say, some fugue or otherwise contrapuntal music.
Meh, it's a toolbox: use as directed, apply directly to forehead, and drop some science, son!