For the odd small drywall repair around the house, I like to keep on hand a small packet of 15 minute mud powder. You can mix up a little, apply it, and then sand and apply another coat soon after, so you can get the whole job done in an afternoon. And it never goes bad.
I take it back… it’s 5 minute mud. Sounds like an insanely short working time, but it’s just to take care of only a few little dents in a small area, and it gives you very fast turnaround.