My impression is he got Zeiss or whoever to send him ten lenses and he'd pick the best and return the rest. Product variation was more of an issue in pre-computer aided design days, which is one of the reasons I'm wary of people who unconditionally sing the praises of old Leica lenses. The finest examples are stellar, the rest are so-so.
Deep in my memory is a commercially available sub-f/1 lens from the early 1970s -- sticks in my mind as a Canon mount, something like a 90 mm. Anyone remember such a lens?
I remember too that it was way out of my price range.
It depends on how old the old Leica lenses are. According to an old Leica Magazine, Leitz was the first lens manufacturer to design and use a computer to help design lenses and that was before World War II.......Regards!