That last part is exactly why I charge $999/hour.

I'll offer a specific solution that takes me a week of full time work (14 hours each day -- I'm focused) for about $10k, which is roughly $150/hour if you want to calculate it that way, or another specific solution that takes me 3 weeks of 10 hour days for $15k which amounts to $100/hour. And like any good consultant, I'll eat the cost if I'm wrong. Other times I'll charge $40k when I know it will take a few months of dedicated work and I have to really lock in.

In practice, I never actually charge hourly. So the $999/hour is really Schrodinger's rate.