Mankell only wrote around a dozen Wallender novels. They were more than police procedural but reflected his broader views on all sorts of matters. He has written other novels.
There are 3 different filmed versions of most of the Wallender novels -which is enough!
Distilling these long novels into TV shows still allowed depth of character and breadth of subject etc.
But the gravy train arrived at the station and with the exception of the opening show (from the last and rather poor Wallender novel) in the current series recent and current films have just been hack work where the script writers do not start with a 500 page novel and worry how they will distill it into a tv film; but think how they can pad out a tv film.
Mankell has provided some script outlines in the past but the back of even his envelope is not the same as a 500 page novel that he has spent years writing.