So, I found Steve Sailer's analysis of PG Wodehouse to be very interesting in this regard, as it seems to indicates that one's forties, fifties, and even sixties are the writer's prime novel-writing season.
The consistency of ratings over time is the most striking fact. But a few temporal patterns can be discerned due to the huge sample sizes of raters. My Man Jeeves at age 37 was a rookie effort, falling 0.13 points below his career mean. Wodehouse hit a long peak from his early 40s into his early 60s with six straight Jeeves novels rated above his career average, but his ratings slip only marginally in his old age....On the one hand, one could argue that I started writing novels too early. Or, at least, publishing them too early. Wasn't it Hemingway who said that everyone had a million worthless words inside them that they had to get out before writing anything decent? I'm finally past that point now, and it is encouraging to know that I'm likely on the left side of the career arc, and so long as I put in the effort, can anticipate continued improvement over the next twenty years.
The peak is probably 1938's (age 56) The Code of the Woosters. The topical political satire of Oswald Mosley, leader of the British Union of Fascist Blackshirts, as Bertie's nemesis Sir Roderick Spode, leader of the Blackshorts, makes the book stand out.The next novel was 1946's (age 64) Jeeves in the Morning (formerly Joy in the Morning), which Wodehouse had a lot of time to work on while he was interned by the Nazis (he was caught at his beach home in France in 1940). It has equally high ratings as Code of the Woosters, although fewer raters. In 1982, Alexander Cockburn designated Code and Morning to be the peaks of the series.Ring for Jeeves (age 71) is the most obvious dud, but Wodehouse rebounded well. For example, Stiff Upper Lip, Jeeves, published when he was about age 81, garnered above average ratings from over 3,000 raters. That's pretty extraordinary.