OK, you know how for the regular counters (as part of the counter block) behave, where 0 is one digit and the number of digits increase only as is needed? We need to be able to do that with custom counters.
Subscreen: Zelda 1 style counters
For the number of digits, use 1. It will expand as needed.
My next question is why didn't I think of trying this already...
Well, it says "Digits", not "Minimum Digits". I wasn't sure myself until I did a test on it. 😃