I hit everyone 2-3 times a week. Usually following a setup similar to DC but geared more towards the powerlifts. I think hitting a muscle once a week is just dumb. Muscles start recovering immediately. It's not the muscle that takes forever to recover, it's the CNS. If you properly manage your volume, you can hit the same muscle more than just once a week. Otherwise all those olympic lifters training the same lift every day would be dying and/or all tiny weak nothings.
Consider the fact that after lifting, protein synthesis in those muscles is elevated for 36 hours at best, peaking at 24 hours out... If you are only hitting that muscle once a week, you are only getting 36 hours of elevated protein synthesis in those muscles each week, you hit a muscle twice a week and you get 48 - 72 hours of muscle growth in each muscle every week. Seems kinda like a no brainer to me.