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Track as you note is not twisted. Track however is also not close to other wires that might create interference.
So what are the major sources of electrical interference on a model railroad.
twin coil switch machines.
Relays without some form of snubber.
It does not hurt to twist wires but I don’t think it is necessary unless some of the above or their supply wires are within a foot of your DCC bus. Having your bus wires very close too each other does increase the capacitive load on you DCC drivers. At DCC frequencies this is low and your locomotive decoders provide a far higher capacitive load. Twisted wires also reduce the inductance that your DCC drives sees. This will reduce the need for snubbers at the end of long DCC buses. The need put snubber on will also depend on how your decoder deals with the spikes. A well designed decode will have no trouble with spikes but it does add a few pennies to the cost.
The only other thing is that twisted wires will reduce the amount of noise your DCC bus imparts to other sensitive circuits such a signaling and detection. PC serial buses are also somewhat sensitive although the sensitivity depends on how poorly it was implemented. A well designed PC serial bus will have no problems regardless.
I am not using twisted pairs and the run is somewhat more than 30’. I have a life time of professional experience with this sort of thing and so I will have no problem sorting it out if I do develop problems.