I once had to learn 4/5 songs in an afternoon for an impromptu recording session later that day. Thing is, I was told about it when I didn't actually have my bass to hand, so I had to kind of learn the songs through listening on YouTube only until I could get home and physically play them. None of the songs were all crazy difficult and I have a good ear so it all turned out fine in the end. Not perfect, but certainly passable. Looking back it was really quite a fun experience.