Balance Finger

[Stuporman]

In reading a tin whistle tutorial, I’m getting the impression that I should cover the 6th hole as a balance finger whenever I’m playing an A, B or C on a high D tin whistle. Ar first it seemed unusual but it seems that it isn’t that difficult a habit to adopt. It’s supposed to balance the whistle and keep the fingers closer to the holes. I’d like to know if this is a good habit to get into. To complicate matters I would like to take up the flute once I get better at the whistle, so I don’t know if using that balance finger system will be beneficial or detrimental to the flute later. Thanks.