Not an answer. No idea why there's the point issue.
On bi-weekly mortgages - as you note, there's no magic to the math. Take a 30 year mortgage, and make a 13th payment each year (right? A bi-weekly has the payment every 2 weeks, so 26 payments a year, i.e. 13th payment in total over the year) and the result will be nearly identical. What the lender likes about this is the fact that they usually charge the interest rate the 30 year term offers even though the mortgage will run 22-23 years.
You also lose any flexibility the 30 year gave you. I know people paid bi-weekly, and they talk about the 2 extra paychecks as money from heaven. Their monthly budget accounts for 2 checks a month, and this extra money can be used to pay off a bill (24% credit card) or just go to one's emergency fund. OTOH, I know people paid twice a month who were sold on the idea of the bi-weekly mortgage and a few months in, were sorry they did this. I was paid bi-weekly for decades, and it flipped to semimonthly. Would that mess up your budget if this happened to you?
Keep in mind, if you pay an extra 1/12 (8.33%) each month on your 30 year mortgage, you will see the same benefit. If having that 3% debt bothers you, pay even more extra each month. But, if and when rates go back to 'normal', you may find that putting the extra money in CDs yields a better return.
(Note: There is a slight effect for the fact that more frequent payments are made. 1/2 the payment is an average 1/2 month early. Say the payment is $1000/mo. $500 is 6 accumulated months early. So, at 4%, this effect result in about $10 over the course of the year. I offer this because years ago, after I published a "bi-weekly" analysis, and concluded that "all of the benefit was the result of an effective 13th payment", I was set straight, there's the savings that would occur even if a bank accepted 1/2 payment twice per month. About $10/year in this example. But not zero.)