I assume avoiding any issues popping up from having to remember to do that is worth the reduction in state space.

(10 + 23)^5 = 39,135,393 which is enough for company devices

I assume there’s a row or column that this applies to in their sheet. So I’m suggesting instead of having some regex applies to check the values. Just setting the entire row or column to text would resolve the issue.

When he says "various google sheets" it sounds like new ones are occasionally created so you would have to do that each time a new one is created. It's extra friction which you can easily avoid.

But he’s putting a regex into the sheet? Unless he has some tool to look at the spreadsheets in gdrive and applies the regex to them? Guess we lack info from the OP.

The regex goes into their UUID generation routine, to stop it from ever generating another UUID with an E in the middle.

When generating human readable alpha codes, never include vowels.

Avoid generating codes like FARKU, WANKR, USUCK etcetera.

Why 23?

Guessing no I, L, or O to avoid confusion with numbers.

At that point I feel like you should just use base32 instead of 33.

For just removing digits-E-digits, that's 10000 patterns for each E position, of which there are 3. Since 36^5 is over 60 million, you're only removing a twentieth of a percent of values. Closer to a tenth of a percent if you remove those values from 33^5 or 32^5.

It's more useful to look at the total amount of values rather than how much the space gets reduced. If you have 10s of millions of values you can have several devices for even the largest employers that exist today.

It was I, O, and E.