Specials are a bit of a different case to a specific model like the Skipper though - it's easier to add an additional print to an existing dial than set a new one up. You can even do it after the event, as the difference in printing of the logo often shows.

I can't imagine a discrete model ever being made in the 10s, that sort of short run wasn't economical for Heuer back then - they weren't selling at the price some of the haute horlogerie watches do now, they were priced within the regular range.

No idea where Hodinkee got the "less than 20" figure from.