@ct when do you use tempo squats, deads, chins, etc… (3 up 3 down)? What are you trying to solve when you program them in? Is it muscle weakness like an inability to recruit quads in a squat?
I rarely use slow concentric tempos, except with isolation exercises to improve mind-muscle connection. The exception is when I want to work on technical precision, then I might use slowish concentric tempos on squats and other complex movements.