Are patch bays really used any more? When I've seen them in recent installations they never seem to be used. I imagine modern routers have pretty much removed the need for them.
Although it's still good to be able to over patch a dead router to stay on the air with a key camera chain or source, but that's usually done with a secondary device, such as a relay box, or small router. It's very rare these days to totally lose all of a router, they all (should) have back up control boards.
Patch bays can still be useful for 'edge' cases, adding flexibility, and allowing for ad hoc installs that weren't necessarily foreseen. They are far smaller in my experience, than they used to be, but you do still have them, particularly downstream of interface glue, particularly if you are using fibre downstream of your router.
Sometimes cameras and primary sources are interleaved
across several input cards. US broadcasters like to do that I'm told ?
UK broadcasters do too.
AIUI both Sky and the BBC have used 'salt-and-peppering' extensively in their recent builds. Does make configuration a bit less intuitive - Cam 1 on input 1, Cam 3 on input 2, Cam 2 on Input 21, Cam 4 on input 22 etc. on a VM for example... but lose an input card, you only lose half your cameras...
SImilarly splitting facilities across router crates is also common, with the two crates NOT co-sited.
Audio departments, particularly in the UK, still like to have acres of patching, despite modern desks having a great deal of routing functionality built in. Folk on the European mainland are a little less conservative, and often raise their eyebrows when they get inside UK sound control rooms.
Ghilmetti has made the patch bays a lot smaller though