Improve quietly enough that your comparison remains internal.

Improvement that gets announced starts to serve the announcement. You begin optimising for how the progress looks, and the internal measure quietly gets replaced by an external one. Keeping it quiet protects the honest version, where the only person you can fool is yourself and you know when you are doing it.

Try making a change this month without telling anyone. No update, no post. Notice whether it holds differently when there is no audience keeping score.