Scouts Out! Cavalry Ho!
I can tune if one string is good. I often play by myself, so it doesn’t matter if I’m exactly on or not, but with others, I need to be exact.
I also have a harmonium (small Indian style pump organ) but they’re never on standard tuning. So sometimes I tune to that if someone else can play it. Or someone else plays guitar and I can play the harmonium. Wish I could do both at once.