This is also one of the instances where the suvivorship comes into play. I think that's the tem that's used.
When Bulova produced the Tuxuedo, they may have made quite a few of them, so it is not that "uncommon". How many do we see (I think they use the term scarcity or some such)? They are not that scarce.
Then there is the suvivorship. It was not uncommon by production numbers, nor is it that scarce to find these days, but since folks were highly motivated to melt the watch and band for $$, the likelyhood of suvivorship goes down, making it more sought after by collectors when a complet watch does surface.
...and I remember reading in more than one watct collectors guides that the term "Rare" referred to a exact model which had 25 or less units produced in total. They did allow subsetting by production year, in case 20 were made in one year and 25 in another.
eBay sellers don't like it when I say I remember reading this...