So difficult to answer without seeing the individual lift - obviously different body types, amount of muscle they're holding, training experience etc all come into consideration. I think the best example is compare how Stan Efferding used to squat (super slow eccentric, but explosive from the hole) compared to Andy Askow (literally "falling" into the hole and uses the momentum to quickly reverse - almost gets halfway up on the reversal).....it seems from my experience that the more muscle you have, the more you can get away with being slower on the eccentric. Saying that, I will still teach the slower, unexplosive lifter to get up out of the hole as fast as they possibly can, even if it doesn't come naturally....seems to always have a positive impact on the speed, and in return strength they can put into the squat. It also seems to be helpful across the board to used the hole as a "spring" (same as an Olympic lifter) meaning that even if your decent is relatively slow and controlled, just before you hit the hole you release and explode up. Hope that makes sense.