At the end they talked about a “large sample size” being 100-200 rounds and not basing the “lack of needing to clean” on smaller sample sizes. 
Sorry to say, but 100-200 rounds for my .17HMR, .223, .260, and 6.5CM would get shot in most dedicated practice shooting outings. With shots on varmints in between and a lot of times on the way to shooting spots. I make it a point to shoot once a week minimum now that I’m in Arizona full time. When I was in Northern California, managing my ranch and other properties for ranchers and the DNR, I would easily shoot 100-200 rounds 6 days a week. 
I’m in the camp of trying to make an effort to take apart my rifle every 1,000-1,500 rounds. Sometimes I only clean the action, bolt, and junk that gets in between the stock and barrel. Sometimes I’ll clean the barrel which is minimal cleaning compared to what I’ve seen other guys do. 
I notice after a barrel cleaning that, if anything, the “groups” open up a touch until 50ish rounds are through it. Not enough to notice for killing varmints or large game animals, more so for shooting ragged hole groups at 100 yards. 
This is specific to Sako and Tikka barrels, which, in my opinion are some of the best barrels in the world. They just honestly don’t mind running “dirty”. I finally shot out a fluted Sako .260 barrel after 5,500ish rounds. It was only cleaned once at 2,000 rounds. Would it have lasted longer with more regular cleaning? Maybe so. 
I’ve noticed other barrels needing to be cleaned more often with groups opening up with very low round counts. Personal use on Bartlein, Christensen, proof, Remington, Weatherby, Volquartsen, and browning with multiple sample counts of each). Many of these guns started showing a noticeable lack of accuracy around the 400-600 round count. I’m honestly not interested in shooting guns that fail to shoot within a reasonable cone at 100 yards with such a low round count through the system. 
I guess the long story short in my experience is… Some rifles and barrels need to be cleaned more often than others to maintain accuracy and proper function. Those would be rifles I am not interested in shooting no matter how accurate they may have been upon initial function. I shoot too much to have to worry about cleaning a damn gun every 400 rounds.