My BFF did it recently. She got really bored. But she's used to Crossfit which is constantly varied, so that could be the reason why she was so bored. She did see significant strength improvements though.
I've done something similar. I like it, but I really like routine. I typically plan my workouts in 12-week cycles anyway, so it worked for me.
I don't do "traditional" cardio-- mine is all kettlebells, balls, ropes, and body weight stuff, but yes, I did cardio, usually for 15' (of intervals) a couple days per week.