More Words, Deeper Hole

Mysteries don't have any need for worldbuilding and readers don't expect character development (just like early SF) but they do expect the crime to be solved. Still, I can't stop myself from providing counterexamples:

There seems to be a hard limit of about 400 pages over in mystery.

Iain Pears, An Instance of the Fingerpost, 704 pages

Mysteries also eschew the cliff-hanger ending and the book-fragment approach

In Carole Nelson Douglas' Midnight Louie series, the primary love interest makes his first appearance in the final sentence of the fourth book. A later book opens with the main characters making a lengthy list of all the murders from previous books that hadn't been solved yet. I stopped reading when a fairly major cliffhanger was not resolved in the next book.