Some automatic programmes adapt their sequence to conditions detected during use. A changing estimate can therefore be part of the intended behaviour rather than a broken clock.
Understanding this situation
The model's description matters. An update is different from an unexplained repeated stop, warning or failure to finish, and the initial display is planning information rather than an exact guaranteed minute.
A useful next step
Let a safe supported programme proceed normally. Keep the load and final result with any persistent timing concern. Avoid repeatedly opening the door or changing settings to force the original estimate, and stop for any safety-related symptom.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.