Whenever I look up a tab for a song and see "tune down half step" I usually just don't do it. It sounds close enough in standard tuning for learning how to play the song.

But for the other more messed up tunings I end up just not even trying the song because I can't be bothered to mess with my guitar just to play one song

What do people usually do when it comes to changing the tuning - just find a specific tuning, then leave it like that for a week or something and learn a bunch of songs in that tuning? Or do you just get used to changing the tuning as you move from one song to another?

I always wondered about bands where they'd have like 3-4 different guitars, but now I'm guessing part of this is having a guitar there in some other type of tuning (as well as to give a different sound of course).

What are some non-standard tunings that you see frequently? Are there basically limitless possible tunings or only a few that actually work?

I figure I need to find a couple songs at least in a different tuning, then just spend some time with my guitar in that tuning and learn the songs, then flip back and forth as I feel like it. Just don't like messing with my tuning every 5 minutes as I move from song to song!
well only if i like the song alot i change my guitar to an unusual tuning....for me having 2 acoustics, i always keep one of them 1\2 step down...And i keep My capo also around~

the most used alternate tuning : drop D i guess or Drop C....Other tunings are very limited to couple of songs i usually try em just for the sake of making sure they sound good
Personally when i want to learn a song i change the tuning. Often the way i tune is either the easy way or the common sense way. Easy way is using a tuner, my acoustic has one built in. Now for my electric guitar i tune by ear, but just think how you can tune it differently. Like tuning to Eb tuning i first tune the A string but instead of tuning it to the A on the fifth fret (of the low E) i tune the A string to the fourth fret...and go from there
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Personally, like you i ignore the change in tuning untill i have to play the song live or something, then for vocal purposes i tune down. I use to not tune down because it was such a hassel, but then i started and i found its not as much of a pain as it seems.

As for other tunings, a common one is open G, where the strings are tuned (low to high) DGDGBD. The rolling stones later stuff is almost exclusively in this tuning, and lots of stuff by the black crows. There's also open E which is EBAG#BE (black crows "she talks to angels")

i also just the other day saw a funky tuning by this guy named Andy Mckee, who is an AMAZING acoustic guitarist. He tuned his guitar ECDGAD and put a capo on the 4th fret that covered the four low strings, it was the coolest thing i've ever seen and the sweetest song i ever heard, Rylynn....its on youtube