I think the weird part for me isn't the shared calendar event, but the recurring thing. I'd have no issue if friends started sending me invites for things I agreed to, or with the expectation I might say yes or no..but a recurring thing makes it really awkward when you decide you don't feel like it that month, or want to end it altogether.
You just say you can't make it each time for 2-3 of them, then explain things are just busy and you don't want to keep cancelling so let's remove the recurring event until you've got the time again.
What's awkward about that? It's basically just the standard way to gracefully end anything recurring, whether it's with friends, a unnecessary business meeting, participation in a club, etc.
