Equivalent belts in general are interchangeable, not just inputs/outputs. [virtual-signal=signal-1] E.g. take the 1-5 from "Loopback substitution". [virtual-signal=signal-2] The three output splitters are all 1-2, so their inputs ([item=fast-transport-belt]) are also balanced with each other. [virtual-signal=signal-3] Which means this belt is also balanced with the other three. [virtual-signal=signal-4] The four belts are interchangeable, so this is also a valid 1-5.