I understand your point.
At the moment this is a bit out of scope because this changes from time to time.
I will try to enhance the documentation later this year at that part.
WEB_CONCURRENCY: Would you be happy enough with a remark within this page: https://docs.zammad.org/en/latest/prerequisites-hardware.html that will tell the administrator that he might need to fiddle with variables if his workload changes with a link to the ENV-page?
Personally I don’t think setting those settings automatically is the best idea. While I do have 20 Agents on my installation, basically 2-3 agents are using it concurrent (there’s never more, even more like less than that). Also, if you raise the concurrency, you’ll also need RAM to ensure everything is fine.
Doing that automatically is imho a really bad idea. Beside that we can’t set ENV variables without restarting the application which might not work automatically as well.
I think tuning options really should be a manual part. Just my Cents