Basically optimize the guitar for the musician. Just the other day I had to file an acoustic saddle to compensate for the intonation of the 2nd string. Other than that, it's pretty easy. I know few people around the world I trust with major repairs. It really depends on the guitar, and the conditions of the tour.
Outside venues tend to make instruments change more, requiring more adjustments.
Again, it really depends on the individual instrument. I use my Peterson 450 strobe tuner to tune every string on every guitar on every song every night. I could not do what I do for Mary Chapin with out my Peterson. Time management is pretty important I think. It is not good when things fall apart during the show and it becomes a repair of a strap button screw hole, if not a big guitar repair.