if you read down you find that he comments about the knot percentage strength varies with the line brand.I have found that it varies with the line brand,the eye type and size its tied to,and the line size within brands. That's why it does help to test a typical setup that your fishing with. It doesn't take anything more than your fish scale to get a pretty accurate reading.
disclaimer: I am not a professional anything. I am talking just like in a tackle shop or coffee shop as a form of recreation. But I'm not in the habit of telling whoppers anymore than any other fisherman.