Grading with the box blade has everything to do with the length of the top link. The box blade has a front and rear blade. The front one, hangs lower. Even at a level side view, it's set to dig. Extending the top link to ride on the rear blade, helps to smooth things out.
It is NOT just about lifting up the 3 point hitch.
It takes practice. If you do a lot of grading, a hydraulic Top and Side links make it so much easier since you can change the angle of the box while still in the seat. Make a hydraulic adjustment, see how it changes what the box blade will do.
Manually adjusting the top link, takes time, energy and you have to get off the tractor!!