on the same topic of those towers
Instead of filling from North to South
Isn't it easier to assign one flex to each tower? They  look at the tower they are assigned, if it's a ONE tower then they know they need to move to a different one, which one? the one with more than 2 req. There will never be any misunderstandings because there is only ever one tower with 3 or 4.

You may ask isn't this more flexing?
well both priorities have 3 flexers but having them assigned to a tower is probably a more set in stone type of deal and should be a more consistent check imo