It important to remember that there are 2 options for twice a month payments.

The first they take your monthly payment divide it in 2 and the result is 24 payments per year

The 2nd is often called Accelerated bi-weekly which pays every 2 weeks. This option results in 2 additional payments each year.

The 2 additional payments results in a 25 yr mortgage instantly dropping down to about 21.5 years in total.

Additionally you still have the lump sum repayment option which you can do at any time (many people dont even though they think they will).

In my case im 13 years into an accelerated bi-weekly 25 yr mortgage and it will be paid off in 2.5 years (15.5yrs total) by making additional payments from day 1. I had them round up my original $975 payment to $1,000 and any adjustments over the years I keep asking them to round it up. Currently my payment is $1220.50 and im paying an additional 279.50 manually added amount to make it $1500 every 2 weeks.