I have many but as a player...
The first one to mind-
I was hired to do an 8 hr session. I was to write and play the lead guitar part(s).
A couple had hired me. He wrote songs and his wife sang.
They hoped to get at least two completed tunes from the session.
They had friends come from out of state for the session. He was to cover all the acoustic work and she was to cover the keys.
The bassist was a guy I had heard of that played "Up With People" trips and at that time slap and pop bass was his thing...on everything lol. (these were rockin'country tunes)
The drummer I had heard play. Very steady, simple and average honky tonk drummer.
They spent like what seemed forever trying to get the drums sounding right...I sat in a booth ready, listening to all the racket.
Bass player slappin' and poppin....Ed, the acoustic player had turned engineer/producer and his wife was playing any and everything she could think of....I sat in the booth, ready.
While waiting I knew Ed turning into engineer/producer wasn't going to do his part(s) and got my head ready to cover the acoustic guitar part(s).
Wasn't long and he stuck his head in the booth and asked me to...no problem.
Finally a run through. They kept the tracks and let me lay down the lead. Then they spent the rest of the 6 or so hours trying to get the other parts...total gas. Nobody had prepared for any aspect of recording in a studio and their parts?...not good. That was a very long session to me.
There is more than knowing ones part and how to lay it down. There is studio etiquette.
They were all upset with each other. Each being right and each at fault.
I unfortunately had many sessions with players that really didn't know how to prepare for a session. Many of them were excellent musicians and handled their part but....there's more to it...and if I'm not clear, it may be something to pickup on if you're planing on paying for studio time.
They got a rhythm and lead part for their money...so they said. Pretty sad really.