Remove more than 1/8 inch of material in one pass without straining the machine. This would cause the engine to labor, the belts to burn out, and the carbide cutters to be damaged. The worst-case scenario is the carbide cutters, spacers, and shafts would break loose, causing a workplace hazard.
Step cutting is a better alternative. Take two 1/8-inch passes, for example, if you need to remove 1/4 inch of material.
The first pass should be made north to south, and the second should be east to west. By doing so, the material can be removed evenly to depth while compensating for any height differences in the surface.