I feel like I’ve spent a lot of time on short stories the past couple years. I just counted, and I’ve worked on twelve this year (some of which were begun before then, and some of which are going nowhere). Sometimes I wish I’d started writing with short stories instead of novels. The learning curve feels faster, since I can actually finish a piece quickly and work on things without getting mired in the plot. I can experiment with different genres, characters, and settings more frequently. I don’t even mind revising them (much), unlike novels.
(Of course I couldn’t have started with stories, because back then I read mostly novels, didn’t like short stories much, and all my ideas were for novels. So starting with short stories would have meant forcing myself to write boring things that I’m sure would have been met with “This sounds like chapter one of a novel”.)
The best thing about short stories? They’re a nice break from the long slog through a novel.