I agree. I don't think I've gone over an hour, but on my upper body workout, I'm consistently b/t 50 - 55 minutes since the bent over dumbbell rows and bicep curls are done one arm at a time. As for my lower body workout, that takes roughly 40-45 minutes (Like Ivydee, I also do obliques in addition to abs, but I just do one 15 rep set for each side).
If you were having trouble finishing your cardio in 20 minutes, I'd be concerned.
...Jason