I spend about an hour to get things ready the night before -- assemble the equipment, weigh the grains, pour out the water for dechlorinating, etc. On brew day it usually takes me 8 hours. But, I don't have a dedicated brewery -- I brew in the kitchen and have to haul out everything and put everything away every time -- and putting everything away includes drying stuff so that nasty mold doesn't grow. Also, I have to reassemble the kitchen when I'm done, and I always mop the floor to keep my wife happy. Then the day after, I tuck everything back on the shelves and go to my job (and tucking takes about another hour).
Four hours for all-grain seems extremely short to me! Even assuming a 45-minute mash and a one-hour boil, I don't see how that can be done -- unless you buy your grains pre-crushed, have very hot water coming out of your tap (so no time needed to heat water), use a counter-flow chiller, brew outside where you can just hose everything down when you're done, and have a permanent stand-alone system that doesn't have to be put away. I used to help out at a brewpub that basically brewed on a half-barrel homebrew-style setup, and even that took 7 hours minimum, usually 8.