DH,
I think that you are referring to an annual (or monthly) payment recast, not the crediting of principal.
I still don’t believe that there is a lender on the planet that doesn’t credit extra principal monthly…
NO loan closes anywhere in the country without a signed TIL.. and with an ARM it isn’t possible to predict the exact amount of each payment over the life of the loan.
I now know that you have read a lot of bad information, and are only repeating what you think is true.