Give your best guess twice over the course of time. Average your guesses.
Your judgment varies from time to time, even if you don’t intend it to. It’s like shooting free throws. Your muscles just don’t necessarily all fire in the correct sequence with the correct strength.
You can use this fact as a way to give yourself a second opinion on something from yourself, given that you’ve let some time pass between your successive judgments. This is why “sleep on it” is a good idea.
You can boost this effect by doing the following:
- Make your best first estimate
- Wait a bit
- Think about what reasons could lead to your first estimate being wrong
- Ask what the new considerations imply, how would they affect things?
- Make a new estimate.
- Average your two estimates.