I'm part of a small group and we have our own pieces, which I'm not allowed to share. But I'll describe the situation and hopefully get the point across. In nearly all the songs in my group's repertoire, different instruments have repeated bits at different points, which means that usually there can be no volta brackets or other repeat signs.
However, we often need to have single-staff scores at hand so that we can actually read the music while rehearsing, otherwise it's impossible due to the sheer size it gets. That said, I can either:
write the entire piece without a single repeat, explicitly showing each phrase again and again; or
use volta brackets and segni etc. in different places, relying heavily on the fact that each score you look at contains a single staff for a single instrument.
When you're writing the flute part all by itself in a dedicated sheet of paper, there's no reason you couldn't put volta brackets around measures 11 through 20 rather than writing them twice, even if the other instruments do not repeat said measures. Right? No need to waste many pages on music that has already been written, read and understood. So let's say I choose to go with that. Now after the flutist plays measures 11 through 20 the second time, they would actually land on measure 31 rather than 21, big picture-wise. Think communication with the other musicians, especially considering they all have different repeats themselves. Also somebody watching the rehearsal and counting the measures would have counted 30 of them so far.
If I don't change the numbers in this way: “Let's play again from measure 21. I mean, it's 21 for me, but it should be 31 for somebody who doesn't have any repeats on their score up to this point. It should be measure 18 for the violinist. No, wait, that is… 17, I think…?” vs. If I do: “Let's play again from measure 31, everybody.”
So in the end what I did is, I put a little 31 over the ending volta bracket (the one that closes measure 20), effectively changing the number of the following measure, which would otherwise be 21. I tweaked it and counted from 31 on, afterwards. By folding measures 21 through 30 into the repeat since they are 11 through 20 played again, I deliberately removed those numbers from the flute score.
Note that the numbers are not actually printed every measure; this is just the rationale.
Is it something that should be avoided? If a pro saw this, would they feel inclined to undo everything and put the numbers as they were, leading to the need to remove the repeats altogether? I'm feeling a little insecure as I don't want my group to have poorly-organized sheet music for posterity.