Without wireframing:
  Idea → Code it (3 days) → Looks wrong → Recode it (2 days)
  Total: 5 days for one page

With wireframing:
  Idea → Sketch (10 min) → Looks wrong → Re-sketch (5 min)
  → Looks right → Code it (2 days)
  Total: 2 days for one page + confidence it's right