In the same vein, length of name vs abundance of other candidate tokens of the same length. By example, in C language, there are only 52 possible one-character names (26 if you stick to the convention of using only lower case characters), 5263 two-character names, 5263^2 three-character names, etc, etc.

It follows that shorter names should be reserved for more restricted scopes where additional context is available. i.e. the use of "i" and "j" as a conventional names for counters, "x" and "y" for arithmetic operands, and "N" for the number of elements in a collection is a good thing. On the other hand, the use of terse names like "atoi" in standard library is terrible, because its scope is in all existing programs (or at least in all C modules that directly or indirectly include stdlib.h