When I had it, I got a good laugh out of the fact the official government advice at the time was to isolate for 10 days from when I first started experiencing symptoms, not from when I first tested positive.
Given that I didn't actually test positive until about 12 days after I first thought I might have it, that means a) I technically didn't have to isolate at all despite testing positive every day, and b) the entire time I had it and was presumably infectious I wasn't isolating because the tests kept telling me I was fine.