When I jump rope, I mix them in sometimes. I do one foot at a time and about 50 per foot (I count these but don't count regular ones, for the reason that I want the same nuymber on both feet). But just to mix it up and get a better workout ont he legs. As far as how my rounds are, I usually do either 45 seconds roa minutes, as fast as I can possibly go. It is a sprinting sort of workout and I go all out for that period. Go 1 minute as fast as I can handle it, rest for a minute, go fast for another minute, sort of like that. I usually stop when I cannot keep jumping with enough coordination any more. I wanted to that crossing the rope thing I see boxers do, because it looks really cool and would prbably help my coordination and footwork, but I ahve not gotten it yet, not even close. Is there any trick to crossing the rope as you are jumping?