This is obviously a "to each his own" subject (as most things should be). Boat ownership to me is a holistic experience, for lack of a better term. I enjoy the time underway but almost as much just being aboard, even on a mooring or in the slip (mooring preferred). And a day aboard just putzing around doing chores makes for a pleasant way to pass the time - even varnishing..
And to me, nicely finished brightwork is a thing of pure aesthetic beauty so I try to keep the most visible pieces up to snuff though I have Brightside-ed Serena's wooden spreaders and other more utilitarian wood parts. I do keep all the topside wood on my sailboat finished bright, but have made canvas sun covers for most of it which has let the varnish stand up through multiple seasons here in the northeast.
An acquaintance put me on to a teak sealer called Semco that kept his 47' sailboat looking snappy. Allegedly just clean the wood thoroughly, then brush on a couple of coats, with a yearly maintenance coat and that's all he claims to do. I used it on Serena's fly-bridge woodwork but decided to try it as a base coat and applied four coats of Minwax Spar urethane over it. Came out beautifully but we'll see how it stands up over time.
Joe