re: When does it make sense, mathematically, to accelerate mortgage payments?

The main factors I consider are:

Do you take standard deduction or itemize?

Do you have other interest-bearing debt? If so, what are the rates and interest deduction status (like student loan interest that you might be able to deduct on top of standard deduction, same re investment property interest)

Do you want to keep a certain amount of liquid assets on hand? If so then can you significantly offset the mortgage interest with high-interest savings or other income investments (short term CD, Treasury rate fund for example)?

Are you maxing out IRAs and other tax-beneficial investment vehicles? Do basic math on that v paying off mortgage.

How long do you plan to live in the current home?

I try to avoid purely psychological moves. And there can actually be liability benefits to having a bank holding a first-priority security- interest position in your home.