Frequent, rapid testing could cripple Covid within weeks, study shows (medicalxpress.com)

So, the key point is that the highly accurate RT-PCR is less accurate than the numbers say, because the results arrive harmfully late. RT-PCR tests quack like a false positive/negative for up to two days, to use the duck test.

In a way it's a classic performance measurement: The metric measured is great, another metric isn't measured and isn't great.