Please do not worry about it unnecessarily because the requirement of at least 1 post in period X is correct from the basic statement

Nah I won't lose my sleep over it, its just that I am always looking for ways to improve this overview and give a clearer picture of local boards activity and that's why I initially went with the most simple solution of counting everyone that wrote at least one post in a month.
I took the opportunity to add this information in my application topic to the merit source.

Glad to hear that there is some use for my charts and good luck with your application (even though I don't think that you will need luck but just some patience).
If you are considering adding something like that, I would suggest not making it a high number. 3 or 5 posts should be enough to call a person active on his local.
If I decide to make some changes, I won't even increase the requirement of posts needed but only add another stat, like how many users with more than x posts local boards have.