[1] The metal is usually brass or bronze that is kept polished, or stainless steel, which requires less maintenance.
[2] In the past, due to the environmental exposure experienced by boats, corrosion and UV damage made maintaining brightwork both Sisyphean and extremely labor-intensive.
The demanding labor of brightwork maintenance has been a storied part of maritime life for some 250 years, since before the days of William Mountaine and The Seaman's Vade-Mecum (first published 1744).
Pinafore, in which Sir Joseph Porter, the First Lord of the Admiralty, recounts that he climbed the political ladder in large part by his ability to "polish up the handle of the big front door".
Lord Nelson might have cast a jaundiced eye on such an attitude, but surely those brave boat owners who persevere in completing their own brightwork varnishing project will feel that they have "gained the most splendid and decisive victory", albeit one that was perhaps "dearly purchased".