And, you bring up a point on weathering that is not often modeled well.
Further, military ships have larger crews than merchant vessels. So, you have a work force available who ought not be left with "idle hands."
HAH! Spoken like a true officer! I liked it when my hands were idle. Do you guys know why man overboards occur?? Cuz you guys always come up with busy work! Bah! ;)
Officer's country will get more repainting, too--partly for being seen by officers; partly (mostly) for the "revenge" of using a needle gun on the brass' quarters.
That's payment for busy work, yer welcome! I always preferred deck crawlers for revenge, myself.
The long and short of it, no one's navy (ever see the Moroccan navy?) goes to sea in slovenly ships, by and large. They may return to port needing work, but they generally do not leave that way. In addition, rust compromises valuable steel on your ship. it is in every sailor's interest to maintain ground tackle, gun mounts, davits, winches and the like.
Now, what people model is a different issue. I sometimes wonder if any bother to look at references. Which brings back a comment by subfixer or ed gruene or maybe bondo on how few underwater hulls are weathered, even when there is significant efforts above the waterline (and often more suited to an East Front panzer than a ship-of-war).
The waterline thing is something that gets me riled.