I've been running one of those Adsense experiments for 55 days now, testing whether it's better to block 3rd-party ads on one of my channels, and it's still only at 83% confidence. It was up to 89% at one point, but now it seems to be coming down again.
It's registered over 4 million impressions so far.
before i pack it in, i was just wondering what your longest experiment was?
i've tested all of their settings apart from this one now, blocking stuff like personalised ads, enhanced text ads, expandable ads, animated display ads -- and so far every experiment has suggested it's better to leave them on.