I second the opinion of silvadel. Variety is key to total muscle growth. I was in the Army for 6 years and I'm now in the Air National Guard, we changed up our routine all the time. There were some people that all they did was the 2-2-2, they could max the PT test, but had no ability do do anything else physical. On a side note, the Air Force PT test is 1 min p/u, 1 min s/u, and a 1.5 mile run.