I had two lunch-time gigs this week, on Friday and Saturday. We were playing at a street BBQ, and in both cases we played from 11:00ish to 14:00, getting on for a 3 hr set.
The musicians came together each morning, with no previous rehearsals, and a set list of about 40 songs, in no particular order. The lead singer chose each 'next song' on the fly, including some that were not on the list, and some that were not in the key of the chord charts we had been given.
On the Friday, I could not hear the monitor, which meant that I could hear myself better - on a fretless, that's no bad thing. On Saturday, we had two guitarists, vocals and keyboard coming through the one monitor, and I was struggling to hear what I played. A 200W bass rig in the open is not that loud.
The low point for me was a song where I just watched the keyboard player, and played the lowest notes he played. The most interesting point was where I tried to keep my bass line flowing, and not too repetetive, when we hung on a D chord for about 5 minutes.
It would have been easier if I knew the material, but their 40 songs are a small fraction of the 700-odd that churches have to chose from, and I don't play them often enough to remember them.
The atmosphere is great, and the people are great to work with, but I am always knackered by the end of it.