Actually requiring 700+ is probably not needed, but I think higher is usually more useful. When you want to quickly burn stamina it's nice to have a strong squad be fast enough to just run through the map, touch the goal and have everyone else run around picking stuff up instead of fighting. Ever since Edeleweiss and her OP passive came out, most of my clears look something like this
After this event I plan to replace St. Paulia with Moonvine which should really jack up the speed, I just hope the team can still clear quickly without double slice.