Depends on the variety of wheat. The STS struggles with harder threshing varieties, hence the need for all the blanking plates and fillers. Rotor just isn't aggressive enough (or threshing section big enough) to cope with tougher crop. The harder-to-thresh varieties in the North can be most difficult with an STS, as the more you close off the open area of the rotor cage, the less capacity you have. But, you have to use what you have so the only general advice I can give is run as few blanking plates or filler as you possibly can while maintaining a tolerable sample. Good luck and safe harvesting.