Rest time in-between Sets

Hello all,

Still on the quest of gaining more mass :) hard work,

Was just reading that for mass exercises, you use heavy weight with low reps and 3 minute rest between each set?

Is this correct, I recall reading somewhere that breaks should be kept to a minimum so the muscle stays stimulated and under stress?

It sort of makes sense because I hear to loose fat you should have minimal rests between exercises to burn fat?

Can anyone give me some info into this please:)