This is true for every account I have had except one. I linked my Commonwealth Bank Bankcard to my savings account so that I could pay my Bankcard through an ATM but had to put a PIN on my Bankcard. It had to be 6 digits long so I used my savings PIN with extra zeros as advised.
I used to work for a debit card processing company, and would like to state for the record that in the USA banking network scheme-of-things, up to 12-digit PINs are supported.