Has anyone out there got a handle on these payment protect loans? Is the following normal?

Have a loan that repaid, was taken out 12 oct .. repaid 9 nov ..(not quite a month) ...
put in $25.00 .. principal repaid to me is $24.53 ... interest paid at .32
So looks like HM and IRD do just fine...

But if had a few thousand loans like this - there'd be a lot of cut and burn ...
So i ask ... is there any advantage at all to the lender?
i thought some of the protect fee was added onto the principal amount at the outset of the loan, meaning a higher principal repay amount owed, not a lower amount!