Compound being a squat, deadlift, press, requiring several muscles. Concentrated is more like fly's, dumbbell curls, kickbacks. My jargon my be off but that is just the way my mind works.
i usually wait til my hardon goes away( watching the hotass bitches look at me while doing a set) then i go back at it...one side effect of Test..lol..
Ussually wait whatever is necessary, if its 1 min then its 1 min, if its 5 mins then its 5 mins all depends also how much effort you put into the previous set, if you do a mad drop set starting with your 6 rep max then it might be sensible to wait about 3-4 minutes