Lot of professional strength and conditioning coaches recommend about 30sec- 1 min of max exertion then rest up to 5 min. It is impossible to do much more than 1 min at 90-95% exertion.
People that are doing 10min exertion are missing the point of high intensity training.
For example.... Doing sledge training, I would pound the tire for 1 min max exertion and rest for 3 minutes for 6-10 sets (depending on time). If I am dogging it, I can last 15 min with moderate exertion no problem. The point is to get the max amount of time in the workout at maximal exertion.