Every exercise in your program should have a prescribed rest time between sets for you to stick to.
Taking the required rest time between sets allows your muscles to recover & replenish energy stores, it also allows you to mentally prepare for the following set. Timing your rest periods also keeps you present in your workout and keeps your focused.
If you go too soon you will be too fatigued & if you leave it too long you wont build up the required accumulate fatigue required to get the results you want!
As a general rule, the rest time between sets is governed by the rep ranges you are performing, the exercise in question & your training goals.
Eg a heavy 5 rep max hack squat could warrant a rest time of between 2-5 minutes, whereas for a 12 rep tricep extension you’d typically be looking at resting for 60-90 seconds.
If you are unsure about how long to rest for give me a shout.
Tristan ‘stopwatch’ Buttle.