yes, guilty as charged. I really do try to NOT do that but most of the time I fail. I mean, even when in 'rote-mode' I can hear a mistake instantly, even if it's a soon to come mistake, and adjust without thinking about it. That does catch me off guard occasionally - - - -
It's not common NOR uncommon for us to change up a song at any time... for example - extending a song if there are many dancers, like a wedding 'money dance' for example.... or more rarely but not uncommon cutting a song short. My band members have no idea I'm behind them to begin with so if they decide to repeat a verse, or cut the song short, not a chance in hell they'll think to let me know.... so when it happens.... YUP, I can get caught with my drumsticks down.
Usually I'm onto it however, almost always in fact... because if they are going to extend a song, or cut a song short, they will do something 'different', unconsciously on their part but I'll pick up on it.... kinda like, "hey, something is different here".