It sounds a little generic and overused but after you've had to refactor several projects and subsequently write them from the ground up, you'll think twice before coding the idea that sounded awesome in your head.
right on! My first ACB ran seeemingly well, until i realized it had a core architecture flaw. Some replanning, and now its 200 times faster and now manages my behavior forest for my game AI
Which leads me to one of my favorite quotes:
"Plans are Nothing; Planning is Everything"
-Dwight D. Eisenhower
and a personal favorite corilary of mine:
"Agile is Nothing without Planning, unless you like getting to crap fast"