I just finished a boot camp thingy a couple weeks ago, workouts were 6 days a week. They alternated cardio days (MWF) and strength days (TT), and then Saturdays were kind of wild cards.
On top of all that craziness, the workouts themselves changed every day. We literally never did the same exercise twice -- except on the last Friday they had us repeat several cardio things we'd done the first week.
They said it was all intentional, in order to avoid plateauing. They used the phrase "muscle confusion" a lot, which made me and my friend giggle.
They advised us to continue switching things up once boot camp was over. More muscle confusion. They said if you do yoga, try adding a spin class. Mix it up all the time.
What can I say? It worked. I gained a lot of strength and endurance in those two weeks. Now the trick is to keep it going.