imo backwards driving is the biggest thing separating good players from great players. aerial shots are of a similar importance, but being able to flip the right direction even when going backwards will allow you to always be hitting the ball toward the other side of the court; they are the biggest diff when i play games against guys that are scrappy and hard to score against vs people who are just able to put up goals but can't make their car do a useful maneuver from anywhere like backwards and flip masters can
But it seems like such a hard thing to practice since it's not really a skill as such, like aerials, it's more of a mental thing