Rest periods were not a thing when I started lifting. You trained and pushed yourself, you rested however long was needed to get the workout done
Did 50 reps on leg press? yep, that might require some rest
Did a set a lateral raises? Nope, probably feeling pretty fresh
Training has a natural flow to it if you FOCUS and PUSH YOURSELF
There is almost nothing about "rest periods"
The directions are pace yourself, be focused, train with urgency, mentally prepare yourself, train to sweat, etc
There is no overquantified bullshit