If you test ONE lens out of a large number, all you are getting is a general idea of what that lens will. Manufacturer's have tolerances. On the other hand, if someone tests 50 or more lenses throughout a production range, I would tend to believe the average results. Sherlock, just because that lens was among the world's best 30 years ago, doesn't mean it still is. Don't believe someone else's test as predicting its performance, test it yourself.
Lenses can vary right off the production line.
Most lens test ONLY tests lenses at ONE focused distance. The inherent problem here is that lenses can easily perform differently between close up, medium distance, and infinity. A great lens at infinity may give poor results at 10 feet, and vice versa. There are not many. Lens tests are done with very fine grain films on a tripod.