I did a gig in about 2000/2002 where I'd been recommended to cover. Couldn't get hold of the band leader, texted, phoned and left messages.
He eventually called me the day before the gig. Said - it's all standards, dress smart/casual, venue is...
I turned up, he said Stick to the roots, nothing flash, watch the rhythm guitarist for the changes.
I spent the next 3 hours playing songs I'd never heard before, trying to work out what the rhythm guitarist was playing - not helped by the fact he was facing away from me further not helped by not having had any sleep for months due to having a new born with colic. 🤣
But yes, at least getting a set list the morning of the gig gives you a chance to at least listen to the songs, but that's not always an advantage based on the "But we do our own version" prolification of bands around.