I didn't re-balance after I started racing them but I did swap my slicks side-to-side after every race weekend. (Also checked brake adjustment.) Slicks can and will move to varying degrees but it seemed like less as time went on and I didn't run tubes. Tubes require screws or beadlocks. I did mark the slicks in line with the valve stem and swapping them helped move them back closer to where they were when balanced during the next weekend. But if you have the time & resources, periodic checks/rebalancing is one of those "nit-picky but good ideas.

I balance my tubed 14x32's (PITA) when I bracket raced a well as my no-tube 9x30s in IHRA Stock. A good friend and very successful 10.90 racer owns a tire store and they always balance all race tires. The Hoosier rep at the races did too. Even if you don't feel an imbalance, especially in lower pressure slicks, it doesn't mean the imbalance isn't there. It can affect the tire as well as the suspension and driveshaft. You don't want any "forces", however slight, affecting the "tune" and job other parts on the car are trying to do.