These days, I change everything that I can from one book to the next. Genre, POV, tense, style, length of sentences and paragraphs, how the chapters and sections are organized, everything.
Neither of your options for how I structure stories feels entirely accurate to how I do things. It’s almost always the story concept first, character second, world a distant third. There are always exceptions: my 2026 sci-fi novel THE SIXTH NIK required tons of world building that couched the whole thing. But I don’t do a ton of stuff that isn’t realistic — TROLLHUNTERS and THE SIXTH NIK are outliers.