That is the fingering I have used for 72 years. It is not a law as much as a help. I'm sure there are times I don't use it but I don't pay attention because I normally don't look at the keys when I am playing . It becomes automatic after time.

MEL
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KORG PA1000, KORG PA900, 2 BOSE S1 PROS, 2 BOSE L1 COMPACTS, YAMAHA STAGEPAS 500, ROLAND VP7