I don't understand why 'i' has been given a pass. The argument boils down to saved keystrokes. Typing is not the bottleneck.
Because it is well enough established (in both programming and mathematics) that it communicates literally no less information to the reader than "iterator" or "index" would in the same context.
> The argument boils down to saved keystrokes.
Not at all. I, for one, find it easier to see the shape of the whole expression when the variable names are shorter.
But apart from that, I think using i,j,k as index variables in for-loop has become such a de-facto standard that I would only prefer long names such as "count" or "index" in situations where multiple indices may cause confusion. But then I'd probably use even more specific names than "count" or "index".
The reason is that in FORTRAN variables starting with i, j, k..n were defined as integers.
Back in the day I learned fortran first, then basic. People that learned basic first often would use the letter 'a' as a loop index instead of 'i'
Now days I still use 'i' but often use indx instead because my editor doesn't highlight single letter variables easily.
I have been using index instead of i in while loops lately. It's surprisingly concise.