To outline or not …
I just think you can do it with or without an outline.
From my very limited story writing experience, it seems to me that it is very difficult (at least for me) to build complexity in a story without at least an initial outline. An outline is like a flexible skeleton. I can bend, take out parts, and add flesh to it.
Hats off to the master craftsmen who craft a complex narrative as it goes on! In Bengali language, we had two contemporary stalwarts reputed to follow these two styles. At one end was Sarat Chandra, who would start with a detailed outline of the story; on the other end stood the mighty Rabindranath Tagore, who was reputed to start with a rough outline of sorts, then would go the pantser way, :-)
As you wrote Tom, styles differ. To outline or not, that is the question. Is that?