How many times can a lump of dough rise?

A while back, I was making pizzas for our playgroup. I made about 14 that time. I actually made a bunch more dough than I needed. I was ready to make about 26. At the end of the day, I was going to pitch the remaining dough. It had already risen 3 times; 1 rise overnight, 1 rise during the day and 1 rise during pizza making. Andrew encouraged me to just round it and toss it in the freezer.

Big question: Should I take a chance and try reusing the dough. Everyone's sitting around the dinner table and I'm going to use it - after I allow it to thaw during the work day (it's 4th or so rise). Will I be serving them a beauty of a pie or an unleavened cracker-like pizza. Here's the final product - oops, none left to photograph.

I don't know technically how to determine when the yeast has run out of food and the dough turns into mush, but, empirically, it's still going strong after 4 times. A very cool observation in this don't-waste-a-damn-thing economy. Thanks for the tip Andrew.