When I started Indentured, it was one book... it was I swear it! but somewhere around 200K, I saw that epic as it was, it wasn't one book. So I thought okay, then, two books... Now nearly 75K into book two, it's looking like three.
I once asked a fellow writer in a writers workshop if he knew things were in series, did he plan it out that way or was that just the luck of the draw?
His answer, it is what it is.
So, sometimes I write series. Sometimes I write standalone.... it is what it is.