Progressive Overload vs. Constant Switching
I'm hoping Anthony and a couple others will chime in here.
From the start of my lifting "career," I have found that I have my best results when I pick a program, stick with it, train intensely, and keep upping the weights. When I start bouncing around, I always have trouble. Now, that might be because when I bounce around I really don't know how much weight to use on various exercises, but I think the point is still the same.
I have been completely sold that progressively increasing the weight you use on the same movement is the way to go. Yeah, maybe switch the exercise in 6-8 weeks, but then you take that exercise and increase weight for awhile, and then switch again.
How does this compare to a lifting style that involves constant changing of exercises, so that you might not see the same movement for 3+ weeks? Is it possible for that style to compete with progressive overload over time?
Also, how about the neural adaptations? Maybe I'm different from a lot of you guys, but if I haven't done an exercise for awhile, when I go back to it I lose 10-15% on my 1rm. It takes me 2-3 weeks minimum to get back to where I was at. Does this hurt the "crossfit" style?