As I understand it, these tests rarely produce a false positive, but often produce a false negative. So a positive test result on 6 occurrences is a much stronger signal than a negative result on 8 days. If you get a positive result from a rapid test, you should either self isolate or take a PCR test to confirm.

Think about what you would do if you wake up with cold or flu symptoms these days - there's a chance you don't have covid, but you still need to be extremely careful. These rapid tests should be thought of as a more effective version of the "do I have symptoms" test everybody does subconsciously every day.