With a $14k fine per violation, I doubt most employers will give employees the option to test weekly. That's too much of a liability.
Especially considering the load this will put on laboratories.
The people that need the test to determine proper course of treatment will get results days after it matters. It will be just like 2020.
In June of 2020, I waited over 2 weeks for the results of my test. A delay that long makes the test more than worthless for preventing transmission and determining best course of action.