Draining gas from ROK VLR 100 carb

The manual says to take the Tillotson carb off of the engine, drain it completely, and do a pressure check after every race. Really? Why? What do racers/mechanics actually do?

I am pretty sure actual race teams do that. I have seen some people completely strip the chassis and service every component. However in the real world I’m sure you can get away with just draining it.