Actually, when I was working with Chuck he usually wrote it three times:
 1. "It can't possibly be that complicated."  Very simplistic model that
 captures the essence of the problem but ignores a lot of the requirements.

 2. "But you have to handle these other situations..." Complications get
 added to handle more and more of the requirements, encrusted on the original
 base.

 3. "Ah, now I see what we need."  Starting over from scratch, he can now
 build a clean implementation that accomodates all the requirements from the
 ground up.

 Unfortunately, many projects end up with an extended Stage 2, and never
 progress to Stage 3.  Chuch always had the courage to grasp when it became
 necessary to abandon Stage 2 and start over, even though it often caused
 consternation for the customer!