Reading the useful responses to the OP on this thread, glad that I have my boat on the West Coast. Where humidity, even allowing that I am berthed on salt water for 365 days per year, is low enough that the interior doesn't need much more annual maintenance than say like the living room in my house.
About 2009, a couple of years after I bought my 1980 built boat, I used Industrial Purple to remove 29 years accumulation of grime and teak/lemon oil or whatever from the interior teak veneer and the solid teak trim pieces. Then applied a rub of polyurethane penetrating oil. Haven't done a thing to it since. After 10 years, I am sure that the appearance has degraded a bit. But still a wonderful natural cherry red (I think Hunter stained the teak). And no build-up of grime at all.