You might have aphantasia: https://en.wikipedia.org/wiki/Aphantasia
a) every time they have to operate the "year" concept they see this mental image
b) when they deliberately want to create an image out of the concept of a "year", they see a circle
If (a) I'm probably wildly aphantasiac. If (b) this is only conceptual art.
You spend some decades thinking "counting sheep" was meant figuratively; you discover that was not the case.
Firstly, this study explicitly prompted people first to visualise years as a circle, so there's no guarantee respondents do this every time - so to answer your MCQ, the answer here would most likely be (b).
However, if you were to ask whether people visualise something (be it a circle or some different visualisation) every time they have to operate the "year" concept, I suspect the answer would be (a).
TL;DR: Aphantasia likely
fwiw, Ed Catmull's Disney survey on this topic is interesting (referenced in the wiki article above)
Perhaps it has to do with my bilingual upbringing: juggling with language was my main job for a longggggg time.