In the last decade, the one insecure time was being called on Thursday evening to do Sunday services at a church I'd never played at before. The place didn't make me insecure, the schedule did - normally, I have 1 to 3 weeks to polish material for a weekend, but they were desperate, and I gave in to their begging. My insecurity was about being the least prepared person on stage - in my normal gigs, anyone who started working on stuff only a couple days before would stick out like a sore thumb. So, I woodshedded like heck for a couple of days, and got the material down pretty well. Got there Sunday morning, set up, and the band launches into the first tune. Crap! - it's in a different key, For a few seconds, while the band plays, I'm figuring out what key we're in, contemplating transposing the thing, then the leader stops us. The guitarist was in the wrong key. Long story short, a few minutes and a few little issues later, I realize..... I'm the MOST prepared person on stage. The band wasn't the best I'd ever played with, but we did fine.