Currently have risers and exh manifolds off one engine, already did impellers on both. I have a list, its long, boat is old and I am a bit crazy. I never complete the entire list, soon after she goes in I start adding to it again. Depends on what she really needs and what I feel like she needs and what I want to upgrade. Last year was nothing mechanical, but lots of cosmetic; really focused on the fiberglass, had some parts re chromed, new boot stripe...this year its mechanical.
As far as the routine maintenance like zincs, bottom paint...its part of my list that never completely gets crossed off, just "checked" that I did it that year. List is prioritized, big PITA stuff first, then what needs to be done before splash, then what can be done after splash.
Goal - is to have it all done before splash so I can make an ass print in any of the chairs and fill up the recycling bins the whole season without getting my hands dirty. Usually happens.