I imagine this might vary for different people, so I thought I'd ask - when, in the writing process, do you decide whether your book is going to be a series or standalone?
I guess this also depends on which genre you write (for instance, fantasy/SF would be more likely to have sequels or companion books) but I'm still curious about how early or late in the process you know, or when it changed for you.
I tend to have ideas that are standalones, and lately I've been wishing my ideas were more "series-friendly" - not just for market reasons, but also because I think it would be really fun to write a series, and go more in-depth with the same group of characters and world. But they always end up being very definitely the sorts of stories that were meant for just one book.