I believe more in instinct training. I don't look at my watch in the gym and panic when 61 seconds have passed. My body lets me know.
Lift,rest as long as it takes you to do it again and repeat.
I'm usually in the gym 1 to 3hours,realistically given the stereotype of the 45 minute rule*for those who believe it* shouldn't I have wasted away by now? Let your body decide