Depends on what type you are doing, and how fit you are, and how long you rest before you do it again. For a very unfit person 10 minutes might give them a heart attack, for a fit person a 26 mile marathon is OK (but not every day!). Many distance runners have joint problems after many years of long slow distance running, that's why short sessions of HIIT 2 or 3 times a week is a superior training method for many people.
dswithers is 100% correct. I'll add in that I don't let my clients do any workout for more than an hour... and that's pushing it. I prefer shorter workouts. More cardio does not mean more or better or quicker results.