Here's one way to get a ton of drives into a single bank.
Each slice of 8 drives in the bank will route to its corresponding P2P tunnel on the bottom. Note I've separated them with cable anchors to avoid any funny business. Same with cable anchors on top of the dense cable to prevent a drive connection.
Since all the tunnels connect directly to the controller and are equal to a length 1 hop, the channels will never route sideways through the machines. The drives will act a bit weird until you get all the tunnels configured with your memory card. For every 32 drives, you'll need one P2P tunnel on the controller. So each controller tunnel is mapping to 4 drive tunnels.
I could extend the length of that bank up to 32 slices before maxing out the dense cable carrying all the tunnel channels, though I would need to reconfigured the controller so that the controller-facing tunnels aren't sharing channels with the dense cable, and to be able to fit more tunnels on the faces. Then I could pop a cable anchor on the end and start a new dense cable line and extend it further still. The only requirement is that every connected machine in a bank must eventually come back to the same controller. No subnetting halfway through. Now while I setup cabling for 2 banks in that image, they don't have to share a controller. I could put each bank on its own subnet, and connect that back to a central controller.
If you want to turn your controller into an aesthetic focal point, this is my favorite design:
The only caveat is the dense cables only have 24 channels left to play with.
