I've never personally trained using relative stimulus. I see a guy at my gym doing some rest-pause and slow negative work. He is leaner and slimmer than am I, but he does look strong on some of his lifts when I notice (DB shoulder presses, for example). I think it can have its place, but I think absolute is probably a better way to go for overall muscle growth.
I could see using relative if there are weak points on which you want to target or if there is an issue with your form on a particular exercise that you want to correct or "feel." Otherwise, Eh.
Complication makes it easy to explain failure.