Feature flags are a release tool, not a settings page

A feature flag answers one question: is this code path on for this person yet. The trouble starts when it is asked to answer others.

Give every flag an owner and a date

A flag without an expiry is a second configuration system that nobody designed. In Sandeel a flag past its date fails the build until someone extends it and says why.

Roll out by percentage

One per cent for an hour tells you more than a week in staging. Watch the number you care about, then turn the dial.

Delete the flag

The release is finished when the flag is gone, not when it reaches a hundred per cent.