Mileage ratings on antennas need to die. They don't need to be justified or even given some degree of legitimacy by even saying mileage my vary.
They are just simply misleading at best, and exaggerated lies in the worst cases. If they were a bigger consumer item I am sure the Interstate Commerce Commission would be all over them. But in the scheme of things there a niche retail item, flying under the radar, except by a few people that know mileage claims never ever did a single person a bit of good in choosing an antenna.
Sorta surprising it was brought up again, as a good part of the gist (or I thought I got this idea across) was even comparing antenna by legitimately measured
db gain figures was not the total answer to be solution.
A good part of bringing back up mileage was for me to slam it back into the ground for the misleading worthless measure of antenna performance that it represents.