Yes, I guess keeping the RPM up is very important when driving a two stroke 100 cc gokart. It is however easy to be carried away and get it too sideways coming out of corners, and then you lose speed. Narrow drifting is the way to go. Going very sideways is okay at corner entry, as you want to slow down anyway. It will only cost you more tire wear.
Jumping in the seat is another trick to bring the RPM up during exits of tight corners at low RPM.
When I drove this gokart, drifting was rather important to go fast, as the spikes need to claw into the ice to generate traction:
RPM was not a big issue, since the engine was rather powerful, and it had 6 gears...