We require these meetings and, if you don't make it, your show is suspended for a month (and you forfiet your time slot, making it available for new DJ's or existing DJ's if they want the slot). You can come back the next month, but you can only take whatever slots are available at that time.
We did try something new last month that allowed one group of DJ's (3 of them who do a show together) to do their show even though they didn't show up for the meeting. We instituted a 'fine' that had each DJ pay $15 for missing the meeting. The 2nd time it happens, the fine is $30. The third time it's $60. After that, they're no longer welcome back.
It seems like a good compromise. We'll see over time how it works.