I do, in fact, know of what I talk. You won't believe me, of course, but maybe you'll believe St. Sheldon's source of much technical information, who says much the same thing:

http://www.sheldonbrown.com/brandt/cone-adjustment.html
http://www.sheldonbrown.com/brandt/bb-adjust.html

It's shameful that hub, bottom bracket, and other rotating assembly manufacturers don't provide specifications for this sort of thing (it's available for just about every other mechanical piece of equipment made). Yeah, no one is likely to check runout of their bottom bracket spindle (not even me, and I've got every thing I need to do so.), but failing to provide the information suggests the manufacturers don't know, which suggests they don't give a damn about how long things last.