So I'm building an fl/ae chunk eater. 256 channels needed, in sets of 8. In the center is the backbone of dense cable, 4 sets to a group, total of 8 groups. Now, you would think that only 8 p2p tunnels are needed on this side (16 total), and you'd be right. But somehow it got in my head that I needed 32 tunnels on the output, one for each piece of dense cable, instead of one for every 4.
Yep, I thought I needed to use two sides of a controller just for the p2p tunnels. And of course, thinking I needed that many tunnels I had the standard 3x3x3 controller, with half of its faces covered by a p2p tunnel. Thankfully, this was all design/testing in creative, so no wasted resources, but still...You'd think that needing that many controller faces would have clued me in sooner.