It would be nice if counters could intelligently choose the number of digits to match the number of files. I'll explain.
I use counters all the time. But, I have to be aware if I am renaming 9 or less or 10 or more files. Or more than 99. If 9 or less, I use the default single-digit counter. If 10 or more, I must choose 2 digits. If I don't, then the files will not sort correctly.
For example, if I rename 11 files using xxx[C], the result will be xxx1, xxx2, ... , xxx9, xxx10, xxx11. If I sort them, the order will be xxx1, xxx10, xxx11, xxx2, xxx3, ....
I avoid this by making sure I use two-digit counters. I thus end up with xxx01, xxx02, ... , xxx09, xxx10, xxx111.
But, it would save me time if the counter foresaw this issue and used as many digits as needed so that all counter numbers had the same number of digits. Maybe, instead of [C] we could use [CC].