The 20 per week limit has been an issue for large organizations with tons of different subdomains managed by different groups. Universities are a good example:

The 20 per week limit has been an issue for large organizations with tons of different subdomains managed by different groups. Universities are a good example: you might have things like bobsmith.faculty.example.edu, cs101.compsci.example.edu, etc., which all count against the example.edu rate limit. This can especially be a problem because the renewal exception to the rate limit doesn't work like you might expect. If a particular cert (meaning the exact same set of domains) has already been created, it can be renewed regardless of whether it would exceed the rate limit - but it still counts against the rate limit. If 45 certs have already been renewed in the last week, you can only create 5 new ones. If 80 certs have been renewed in the last week, you can't create any new ones. They plan to change this, but it hasn't happened yet: https://github.com/letsencrypt/boulder/issues/2800 https://github.com/letsencrypt/boulder/issues/2800 Some organizations have gotten rate limit exceptions to handle this particular issue. Maybe they looked at some internal metrics and decided raising it to 50 would reduce the number of exceptions they have to make while still curbing misuse.