I get this one a lot..."should I stick to the rest periods you prescribed on my program?"
My typical answer - "Yes. Why do you think I put them on there?"
I'm going to make a great dad. But really, the why...
Imagine three pallets of brick, weighing about 1.5 tons each, sitting on a construction site. And your job is to move them 100 feet, by wheel barrow, to where they will be laid.
Now, imagine three different scenarios..
1) You have 3 days to move all three pallets, so one pallet a day.
2) You have 1 day to move all three pallets, so one pallet every 2.5 hours.
3) You have 3 hours to move all three pallets.
Is it a little easier to understand managing rest periods?
I don't care if you can squat 80% of your max for 5 reps if you need 10 minutes of rest before you do anything else in that training session.
Powerlifting is simply 'how efficiently can you do the "work" of moving a barbell in a straight line' (except for bench, story for another time).
So, from a powerlifting perspective...
Squat 80% of your max for 5x3 with 5 minutes rest
vs.
Squat 80% of your max for 5x3 with 2 minutes rest
(assume same bar speed and RPE or level of fatigue experienced)
The latter would prove that you are stronger, with a higher level of General Physical Preparedness, than the former. Or, to put it plainly...
Doing the same amount of work in less time means you are stronger and more physically prepared.