I spend at least a month in the Spring, cleaning, polishing and waxing the boat. It is 22 years old, and I make sure that everything is repaired and in order before the first launch. During the season, periodic washing and vacuuming does the trick. Keeping it covered is a big plus.
When fall comes, I do a thorough cleaning. If the water is not beading on the top coat, I would give it a quick wax to avoid oxidation.
I am blessed to have a carport big enough to keep the boat under. Folks finds it funny, I value my boat over my truck!