For all banana plugs, just drill a lot of 4.0mm holes in a block of wood, install it high enough. Now you just "plug in" the cables! Friction keep them plugged in, gravity keeps them perfectly straight.
Use a big enough plate, with large enough number of holes. This is as close to perfection as it can get.
This only works for anything that has a simple plug that can be plugged in a hole. For BNC, alligator clips, etc., the problem still exists. But getting rid half of the N cables, the N^2 problem reduces by four times, and may become acceptable.