We base final adjustment on the inspections for chronometers and their respective requirements. A watch adapted perfectly to its wearer's wrist - and wearing habits - should have a slight advancement of between 0 and 5 seconds maximum per day.
Of course, one must take into consideration that this performance is only possible under ideal conditions. For instance, when the oils are still fresh and the watch is not subject to external influences such as magnetic fields or water penetration.
Regular inspections by a watchmaker usually rule out the latter.