Psychotic protagonists

Apropos of a new and highly praised mystery, I have come up with the desirable relationship between book length and character psychosis: inversely proportional. That is, the crazier the protagonist, the shorter the book needs to be.

Madness is wearying. Hitchcock knew that. The crazy motel keeper of Psycho makes only brief, but oh, so telling, appearances. Ruth Rendall knows it; her heroes and heroines are frequently beyond the pale but their novels are compact.

At length, too much clever psychosis seems manipulative and unrealistic and not finally any more interesting than ordinary, complex folk.