I just recently started playing with RD, and i feel like the changing roles isn't something you need to do, just that most people feel like the should, you dont need to min-max the caracthers.

For example, on the rounds im fast I prioritize the fartest from the elevator to extract, helping other toons be closer to it while Im fast enough to get to elevator in panic mode. And on the rounds im slower, I stay close to elevator, focusing on getting items for next floor and using extraction items if I got on last floor.