Since "the season" is basically upon us (Advent starts Sunday), check her out in The Hogfather:

• https://en.wikipedia.org/wiki/Terry_Pratchett%27s_Hogfather

> Man, we all talk about how Game of Thrones tanked and took itself completely out of pop culture (before HotD brought it back in full force), but Sherlock should be in that conversation too.

IMHO Sherlock was more gradual: each season got a bit too clever for its own good. Also found the same with Downton Abbey: I was less interested after each season until I stopped watching. (I really liked the first because I had also watched Fellowes' Gosford Park when it was released.)

GoT seems to have run off a sheer cliff.