You can miss out on activity periods if you don't post in one or more 2-week activity periods, right? If that's the case, then we're definitely on the same page, and I still think OP will figure this out once he gets past the 28 activity phase. After that, things should start becoming routine as long as he keeps posting routinely.
Sure.
Let's consider 2 consecutive windows, 28 days in total.
If member A post one in the first window, on any day from day #1 to #14, then make 27 posts in the second window, from day #15 to #28, that one will get a max activity point at 28.
If member B does not post any post in the first window, then make 28 posts in the second windows, that one will get only 14 activity point.