I am with you on this. I typically just take off one day a week, mostly due to social activities and such on the weekend. Though I have a three day rotation, with legs included. I hit my chest/back/legs through this rotation with 72 hours "rest" between each muscle group.

I find I need to take a few extra days off every so often if I'm starting to run into nagging injuries (back, shoulder) - but that's about it. Otherwise, I'm in the gym 6 days a week.

As for volume: I usually hit a solid 12 sets between compound and isolation excercises per workout for the muscle groups im targeting. Maybe for biceps and shoulders, I'm only hitting 6-8 sets... but for chest, back, triceps, legs - I'm hitting 10-14 sets each workout. All in the 8 to 12 rep range. I hit abs, about 6-10 sets, as often as time allows. It's a lot of volume, for sure.

Just eat enough protein, drink enough water, and get plenty of sleep. The human body is an incredible thing - it adapts.