My rest periods vary. No less than 30 seconds, but I try to keep it no more than 90 seconds between regular sets. My recovery for the next set is usually at about 45 seconds, I'd say. But I only do my last set to the breaking point... I do 5 to 8 sets of 12-15 reps, then increase the weight to do the last set where I'm at exhaustion after about the 6th rep. Before that last set, I might wait 2 mins. My goal isn't to get any bigger; just harder & always defined. If my goal were bulking up, I'd be doing it very differently.
Charles