That's not how mortgages work, at least in the US.

There's a limit to how often the rate changes, etc.

Just looking at one now, and it's set up as follows:

1. Rate is allowed to change only on the 1st day of every 6th month (after the initial flat-rate period ends).

2. On that day, the new rate is set to a spread + the max of 0 and the value of the 30-day Average SOFR Index (as published by the NY Fed) as of 45 days before the day when the rate is changing.

Nothing being applied on the daily basis here.