Lenders calculate interest daily and add it to the loan once per month. If you have a 100% offset account the savings in the offset offsets the daily interest so it would not make any difference if you are paying weekly or monthly.
In the old days there were no offsets and people just paid monthly. Then someone come up with the idea of paying fortnightly - these saves a bit of interest but the real effect is that you pay 13 months worth of repayments each year instead of 12 so the extra repayment is what is the main reducer of the loan.