Calibrate
Check the work against the stated intention at fixed points, never against today's taste; correct only the drift.
Pilots cross-check instruments at fixed intervals.
Seen in Ise Jingū, Shikinen Sengū, Ise, Japan, every 20 years (the 62nd rebuilding in 2013)
Try it on your work
Measure one thing you've been estimating by eye (the actual weight, the actual count, the actual distance) and set the measurement beside your standing guess. Recalibrate the eye, not the record.
Write what you expect an hour to contain, in one line, before it starts; when it ends, write in one line what it contained. After five such pairs, the consistent direction of your error is the finding; the errors themselves are just noise.
Take one number your project reports (progress, cost, load) and audit it once against the ground truth it claims to summarise. If they match, trust the number more; if not, the reporting chain, not the work, is the next subject.
How it has been used
Check against the original intention and correct the drift: the piano tuner's fork, the annual re-reading of the founding document, the recipe cooked next to its first photograph. The move forces an external reference: correcting drift against your current taste is how the drift wins.
Where it leads
Grouped under Let me find out what holds up