Just a thought, but if a course specifically made a 15-hole "course" but then had 3 bye holes at the end (say, a par 3, 4, and 5), I think it could really encourage folks to have fun at the end of a round, rather than ending with a grind. Most folks want their 18 holes, but if they only have to post 15, maybe it could create a fun dynamic at the end.
It would allow more room for "unfair" holes, extreme risk-reward holes, and high-luck holes, since people wouldn't have to be worried about their precious handicaps. I think that would be good. At the same time, I wonder what it even means to have multiple bye-holes on a course that aren't technically part of the course. It does seem a bit weird to say they aren't part of the course, when they are, you just don't really have to play them, and I guess they wouldn't be part of tournaments.
Any thoughts on this? Has it been done before?