Then again, it could all be immaterial, akin to debating how many angels can dance on the head of a pin. It seems to me that it would be very easy to see if cables improve with "burn-in." Directly compare "burnt-in" cables with identical "non-burnt-in" cables. Double-blind test, either ABX or same-different. See if a statistically significant number of trials indicate that there is probably an audible difference between them. If not, I don't insist on accepting the null argument; we can do more testing.
And/or do electrical analyses on cables before "burn-in" and after, measuring the conductance and reactance over maybe 5 Hz up to 100 kHz.
And/or do electrical analyses on cables before "burn-in" and after, measuring the conductance and reactance over maybe 5 Hz up to 100 kHz.