Writers who improve with time

Willow writes in the rec.arts.mystery group: "As we all know, some writers do not age well.  Each new book represents a decline.  The example I use most often is Patricia Cornwell, who's [sic] first five books were good and then steadily declined. The last seems to be worst than the ones before. It is nice to see a writer improve. I did not like the first Kathy Reichs book.  While we kept getting them, I put off reading, expecting a disappointment. Recently, I returned to her books starting with "Fatal Voyage" and working forward to the newer titles.  A very nice surprise, the books are steadily improving to the point where "Break No Bones" is a treat and I am looking forward to the remaining titles."

I agree on Patricia Cornwell (James Patterson is a similar example) but not on the Kathy Reichs part. Or at least, not for the first four of her books which I read and then vowed not to read any more because the plots were so tedious and uninvolving. The trouble is, I cannot know whether the later books are better unless I break my vow.

I can't think of examples of series that predictably get better with time. Some I always enjoy, eg Michael Connelly (Harry Bosch), Robert Crais (Elvis Cole), Arnaldur Indridason (Erlendur), Helene Tursten (Irene Huss), Henning Mankell (Kurt Wallender). Others vary a bit in quality, not necessarily predictably, eg Harlan Coben (Myron Bolitar), Lee Child (Jack Reacher), Sue Grafton (Kinsey Millhone) – but are usually pretty good.