you can read what is explained on the
Cable Cooker website regarding the technical details. it basically runs an ultrasonic signal up to 1 watt thru interconnects, and an ultrasonic signal up to 22 watts thru speaker and power cables.
as far as what is heard, my first point would be what Jack said about knowing your own system and sensitivity to changes and experience recognizing them;
as far as specific things to listen for I'd say a few different things which are subtle individually but jump out collectively; noise floor, micro dynamics, refinement, airiness on top, body, and liveliness. basically the overall ease and feel of the music. the degree it breathes.
maybe the easier read is when the cables stop constipating and closing in the sound. it's the transition to greater degrees of openness and ease and agility that is the primary change and that is made up of a bunch of individual things. obviously the higher the capabilities of these areas of your system the more restrictions are perceived. new cables can have higher information but stifle the flow to begin with.
as far as people perceiving extended times for break in it mostly has to do with the agility and degree of harmonious flow. the jump and snap factor so to speak. is there a human component to that? everyone has a right to their own opinion about it.
I have my 20-30 go-to reference cuts I always use to check out system performance. I've used them for 10+ years many hundreds of times with any changes.