The GMT hand works perfect, no need to ever reset it if You don´t change time zones, using my white, classic 16570 Explorer II all the time.
Incorrect hand stack just means the GMT hand sits below the hour hand instead of above. This is noticeable exactly twice a day for some minutes if it happens that You are starring at the watch exactly at that time (which in real life happens maybe twice a Year) and know exactly what You are looking for.
I really doubt a gen-owner would care or know if his GMT hand sits above or below the hour-hand unless he is repairing it (and voiding his warranty).