How to handle multiple magazines on the same subject but on different instances?

How do y'all handle reading and posting to multiple magazines on the same subject? As an example, 3D printing is a hobby of mine. I searched and found 3 different primary magazines and 2 adjacent (see below). Is there a point to the 2nd and 3rd most popular ones? Do I subscribe to them all? Do I post to one or to all? Do the...