Most mortgages do not compound interest daily and that is the reason for this
My second mortgage does, but my first doesn’t. So, I just set aside 1/4 of the amount every week. Every 4 weeks, I make a payment. For the other mortgage, I send in weekly payments and I can see that parts go to interest and parts go to the principal. Over time, I was able to see that the weekly payments paid down a few more dollars each month than the monthly payments did.