Also, even some "pantsers" can get away with seeming to have had a plan all along if they write the project out of order from how the reader will read it/viewer will watch it. You can write the end first, no one can stop you (except maybe your editor because editing back together into the "right" order can be a chore).

(A bit harder to build a TV show that way, though not impossible; How I Met Your Mother almost pulled it off, depending on who you ask, for one instance.)