I use a plastic milk crate, kicking it as i move down the roof. also a convient seat to clean wheels.
I use the 2 bucket method, MF towels & mequiars gold car shampoo. & a quick detailer application after the wash.
washing car article
All depends how fussy you are about the finish, a good wash will take 30 to 40 mins from wheels to roof, less if you cut corners (like the roof, who sees that?).
anyway, 1-1/2 hour per weekend, weather permiting, can keep this car almost perfectly clean, in & out