The reason why it only applies to the most significant digit is that I can say for certain that quantities of 1_ will appear ~2x as much as quantities in the 2_x family. However, I can't say whether numbers ending in 1 are more common than numbers ending in 6, because although 11 occurs more than any number higher than it, it makes up a minuscule proportion of the numbers ending in 1, and 16 occurs more than 21, 31, etc., so there's no clear way to predict what number will occur most in any digit but the most significant.

Thanks for offering your views. My analogy may be wrong or weak and maybe there is a better one to be found.

Every base is base 10. There's your answer.