It all depends on the person, the body, the genetics...not everyone is the same and no one gets the same results from the same workout.
Using myself as an example...I am VERY short (5 foot...almost) so I have very short limbs, so any muscle mass I gain shows very easily. Genetically, I put muscle on very easily as well. Put the two characteristics together and I have to stay with the high rep workouts to get the results I want. When I go heavy, I don't do it for long because I get more muscle mass than I want....I feel I look too bulky.
Now, while I stick mostly to the high reps and the circuit workouts, I do pick a weight that has me lifting to failure.