I've had a military SF novel in the works for several years now, going through two versions (including a complete overhaul and associated worldbuilding) and at least three rewrites to its (more or less) present form.
I then began another rewrite, trying to whip it into better shape when I hit a plot snag. Thinking outside the box wasn't working so I set it down, closed the folder, and tucked it away. Perhaps some time away from the writing was needed to let my subconscious work out the issue.
That was over a year and a half ago.
A few days ago, whilst talking shop over at my favorite watering hole, I suddenly had a break.
That plot snag untangled itself and a solution presented itself like a gift from the heavens.
More like a rake handle thwap between the eyes.