I’m pretty sure there won’t be a fixed amount, and that there’s some degree of discretion.
I have sighted the final appeal response for a ban to one user, who got counts of moderation sanctions in response. Their count was 39 BNBRs. I don’t know if that includes successfully appealed BNBRs or not.
I’ve seen the number 4 mentioned in variants of this question for blocking. I have had 4 BNBRs, but 3 appealed successfully (eventually).
EDIT: Matthew Bates is a data point for 4 BNBRs; I’m a data point for it being 4 BNBRs appealed unsuccessfully:
I’ve been edit-blocked for a week for my fourth BNBR violation. This one came from an answer I wrote over a month ago that already had over 1.2k upvotes.
I do believe someone is trolling me… reporting everything I write and seeing what sticks.
Anyway, I’m going to use this time to work on some other projects. If you’re wondering why I don’t say anything for the next week, that’s why.