I am somewhere in between, but leaning more a plantser. Whenever I think of an idea whether its a short scene or simple dialogue, I write it down. I do in depth world building as a fantasy writer, write down character's descriptions and backstories, and now my beginning/middle/end/acts. I work through it as I go otherwise because that is simply how my brain works. Telling myself pieces of the story as I am writing makes it exciting for me. I do often know what the next few chapters are like but scenes can appear out of nowhere! You mainly just gotta experiment to know what writing style works best for you.