The thing that I got wrong about estimates was thinking it was about estimating. Actually, someone already has a time constraint. There’s already a deadline. Always. Your manager, VP, customer, whoever already has a time budget. Find out what it is and work backwards.

When someone comes at you for an estimate, you need to be asking for the time budget or expected schedule — not estimating.

I failed to understand this for most of my career. Someone would ask me for an estimate, and I would provide one. But without knowing the expected schedule, the estimate is always either too high or too low.

Scope is always flexible. The feature or commitment is just a name and a date in people’s heads. Nobody but engineers actually care about requirements. Adjust scope to fit the date, everyone is happy. Adjust the date to fit the scope and people will think you’re either late or fooling them.