John,
I guess, then, that you didn't literally mean saying hello every 30 days :)
I think frequency of messages will come and go, as ocean tide.
As long as (new) people interested in these things will have ways to find a way to this group,
they will sign up and ask questions, or propose their own topics.
If I remember correctly, I was referred to the group by another member, I think it was Ralph.
Don't know how other people find out about it, and decide to sign up.
If anything, the quite general and all-encompassing name might be making it more difficult for people to understand what the group is about? I don't really know what to suggest as an improvement, though.
Perhaps the group just needs new blood, people with interests in these topics and enough time (and lack of excuse-making) to make some projects and post about them. How to find and attract this new blood? I guess making some projects, and writing blog posts / making youtube videos about them, get them noticed by hackaday etc. All with a link to the group.
Cheers
Gene
