My ratio would probably be 60% sailing & 40% maintenance. Like some of the other posters I find the maintenance work relaxing; bit like getting away to my shed
I think another issue is how old your yacht is. Newer yachts should have less mnaintenance, whilst anything over 20 years old is going to require regular work.
On the question on whether smaller yachts require less maintenance, I think it partly depends on how much gear / gadgets, etc are on board. A yacht used for daysailing only with icebox, minimal instruments,etc is going to be fairly simple to maintain. However a yacht used for extended passages with fridge / freezer, watermaker, multiple charging (wind gen, solar), lots of instruments, etc, etc is going to require a lot more maintenance. The larger yachts tend to have more gear so this is probably one reason why the bigger yachts require more maintenance.