Of no real significance, I offer a wee quirk, FWIW:
Some things I do in sixes (or fractions/multiples of six), some in eights (or fractions/multiples), some in nines (etc.). Some things “require” I do them in sevens, and a very few in thirteens (no multiples, just thirteen, period). There are also certain “calming” patterns I trace–with a pen/pencil on paper, on my right or left thumbnails, or simply between my ears. These always involve nines and are drawn in one continuous line, with no trace-overs. (Patterns derived from these can be found, at times, in my private “Non Compos Mentis Coloring Book”–a collection of doodles made during boring lectures in grad school.)
These, along with visualizing numbers as having places in 3D space and colors associated with different number “families,” are just things I have done since childhood, for the most part.