What if, instead of simultaneous bans...
We made it so both picks in a rotation pick at the same time, like we used to?
The reason that was stopped was for the sake of preventing confusion, if i remember correctly, but since everyone essentially is given their roles I don't see why this is an issue anymore.
Then since you're cutting out a solid 30 seconds (minimum) from at least 4 rotations (2 minutes minimum) we can implement 5 bans properly. And because 4 extra bans is, you guessed it, 2 extra minutes, no net time is lost.