If you have bugs that have cooked onto it and other grime, you still have to scrub those areas, but everything else requires no scrubbing.
I try to wash it often enough that nothing gets caked on, and I can just foam it, let it sit for a couple minutes, then pressure it away.
I have a 1500 PSI pressure washer, even though it is a relatively weak pressure washer - any rock chips or slices in the dip you have from road debris, the water will shoot underneath the dip and you have to carefully squeegee the water out from behind the dip. I just be careful not to get too close to the areas where I have chips.
I rarely drive anymore, and my car stays underground in a garage - so I don't usually have anything to scrub - so the foam cannon is perfect since I don't even have to get out a sponge!