I'd love if we could just put in whatever format string we want, but I suppose teaching everyone how to use %-codes would probably not go so well. That being said, at present we have some which go to seconds precision and some that only go to minutes (specifically, %c, %x %X, and %X %x do seconds, the others don't due to https://github.com/metabrainz/musicbrainz-server/commit/0e77c9e3

Not sure what the solution here is, but we should be consistent.