I change it as needed. Right now, I'm training everything twice...that's right TWICE! I do 2-a-day splits and take naps between workouts. Most of the year though I hit everything once per week, except whatever my weak point is, which I'll hit either twice per week or 3x in two weeks. Everybody is different though, so don't base your strategy on someone elses recommendations. You have to try different routines and find the "sweet spot" that works best. I believe that if you don't occasionnaly overtrain, you'll never know where that threshold is. Every now and then I push harder and harder until I hit that overtraining crash...then I take a week off and get back in it.