This sidetrack has really become a "Discussion" topic, but what the hell.

I would like to add that during that first decade of his writing career, Jack was always trying to broaden his markets so that he could earn more income from writing. He started with fantasy, but that didn't sell (until Dying Earth sold to Hillman; but that was a lucky one-shot, nothing more for almost a decade). He tried his hand at mysteries, but those efforts also remained unsold for another decade. So he concentrated on SF and achieved some success. I'm guessing that he also explored the possibilities of becoming a writer of juvenile novels. Like mysteries, juveniles were/are a broad market well worth trying to enter (just ask multi-millionaire J. K. Rowling!) I can't imagine that Winston solicited a book from Jack, he must have submitted a proposal through his agent. He got a contract, wrote the book, and it did pretty well, being published in the U.S. and several European countries in the next couple of years, his first overseas sales.

But that was it. Perhaps Winston turned down his ideas for a second book. With one book to his credit, he could have sought another juvenile publisher. However, I suspect that he did not find juvenile writing very satisfying, so combined with a turn-down by his first publisher, he probably just gave up on the juvenile market, as he did with fantasy and mysteries.

Fortunately, in the late fifties a cheapo publisher bought his two mystery manuscripts (for a whopping $100 each!), a major paperback publisher picked up one of these for reprint earning about ten times as much as the two hardback editions, and Jack decided to return to mystery writing. In a parallel event, Jack met the editor of Fantasy & Science Fiction, who asked him if he had any of that magazine's type of material. Jack pulled out his unpublished manuscript of Green Magic, it was purchased, and he took up fantasy writing again for this lone market and was later able to expand into paperbacks (greetings, Cugel!)

As I have explained from several angles in my Vance bio, to fully understand his choices as a writer, you need to recognize that he didn't write only to amuse himself. He wrote for money, then chose to write the kinds of stories that amused him.