[konstantinua00]

"common" has such a large spread because meaning behind it is sort of "at least one in each sample", where that sample can be anything (graspable)

if you're a teacher and one student per class does the same thing - it's common. Even though it's only 1/25 or 1/30 of all students

[BobaFloutist]

I think I mentally interpret "common" as "a member of a plurality category," which is to say in the same order of magnitude of commonality as the most common group at a given level of detail.

What you're describing, I think I would call "Not uncommon." Or, to put it another way, you shouldn't be surprised for any given case to exhibit it, but you shouldn't expect it either.