I’m doing P90X Classic and I just started Phase II. I thought it was weird that the first weights exercise of the week is chest & triceps which puts a 1 day break between back & biceps and legs & back. I’d personally like more than a 1 day break between back workouts. I decided to switch chest & triceps with back & biceps so I get a 3 day break between back workouts at the beginning of the week and a 2 day break when I go to the next week. Has anyone else decided to do this or can anyone explain why they have it set up this way?

I don't see anything wrong with doing that. Cept for the fact you might be feeling it pretty bad if your really bringing it during Kenpo X. Personaly, my back and legs recover at a pretty quick rate, if I really wanted to I could do legs or back the day after I already did them if I had too. Plus it is only recommended you have 48 hour to 72 hours between muscle groups. I'm sure having back one day and back again two days later reiforces what your training your muscles to do. But like I said, I don't see any harm in switching them.

i think it is set for endurance, I understand your concern for endurance but keep in mind that you're doing different exercise.

I'd recommend that you stick with the schedule for a week to better assess how you'd recover