Actually, all of the open shuttles have been full with the last few oversubscribed by larger and larger margins (about 100% for MPW6 if I remember correctly).
It was the commercial shuttles, called ChipIgnite, that have had space left over.
I had in mind that OpenMPW-1 was not quite full, and looking now on efabless.com I see 37 projects submitted for MPW-1.
but i don’t think it really matters - there have been lots of submissions for all of them and a ton of cool stuff, and yeah the recent open shuttles are definitely full :)