still the same if u pay by bi-weekly.
worst case u still in loss.

loan 400k
tenure 35 yr
monthly installment 1843.79
interest 4.3%
due date every 1st day of the month
full flexi loan

daily interest 400k x 4.3% / 365 = 47.1232

at 15th of the month
Payoff amount 400k + 15 x 4.3% / 365 = 400k + 706.8493 = 400706.8493
Outstanding amount 400k

Option 1(pay bi-weekly)
Assuming u pay bi-weekly which is at 15th of the month
Payoff amount 400706.8493 - (1843.79/2) = 399784.9543
Outstanding amount 400k

take note that the interest rate is calculate based on the outstanding amount which is 400k and the interest rate will be 47.1232/day
Option 2(offset principle, withdrawal option)
Assuming at 15th of the month, u use (1843.79/2) and bank in to offset the principle, withdrawalable
Payoff amount 400706.8493
Outstanding amount 400k - (1843.79/2) = 399078.105

interest rate after 15th will be based on 399078.105 which is 47.01468/day

Summary, its not worth to pay bi-weekly and a lot of agent is giving false info on this.