I understand what you mean about the sprints, I think, if you are sprinting, you cannot stop yourself from running for the 10 secs rest, so it ends up like some mad fartlek session. Quite hard on the old legs!
I am developing and building up and longer and longer tabata conditioning session, the key is finding the right exercises that fit together. At the moment it looks like this.
4 non stop back to back tabata intervals - total time - 16 minutes of non stop training
1st exercise - burpees. Face to floor, 6 inch jump off floor at top, good form.
2nd exercise - plank with rotations - for 20 sec work period straight plank, for 10 second rest period, side plank, left then right then left again etc.
3rd exercise - jumping jacks
4th exercise - non stop 1-2 on heavy bag.
May not sound much, but it is a very good routine at the moment (I start it after 2 x 5 mins speed rope sprint in place.) The burpees obviously take it out of you. The rotating plank is an utter killer straight after the burpees, because you want to breath and get your breath back but cannot because of the stress of the plank - it is very much like the feeling of fatigue you get when grappling and being on the bottom for quite a while. The jumping jacks are high energy but an easier exercise and allow a slight recovery. The non stop 1-2s on the heavy bag are a good finisher at the moment. I just have to work out the next part of the jig saw to add a fifth exercise. I am open to suggestions ;-) I think it would be good to get to 8 exercises, all putting different stress on different systems. It is easy to make absolute killer routines really, too easy, I see no point in dying training though! I prefer to work hard, but have a quality element to it as well, where the form can remain decent. Please don't suggest pressups or pullups, as for me these are not good exercises for doing intervals to. I use a gymboss time btw, excellent kit.