There are technical reasons why older LTR systems used LCNs spaced out rather than 1/2/3/4. If the home channel were busy, they would use a round robin to determine the next channel to use. If using one, and it selected 1/2/3/4, no problem. But if it selected 5 or higher, it would use channel 1 (the next valid LCN). So, LCN 1 would get the assignment much more than any other LCN and would tax the transmitter much more than the others. By spacing out the LCNs used, each transmitter would have an equal chance of being selected by the round robin (10 may select LCN 13, not 1, if the LCNs went 1/5/9/13/etc.)