Here's my two cents coupled with a little cable geometry theory. I think it has less to do with the wire and more to do with the insulation. In my experience cables with more di-electric material and higher native electrical impedience generally need more break in time. Pure silver definately sounds different than copper or plated silver but all else being equal it's the cable geometry that determines the break in period and how the cable settles in to your system.
Teflon foam or air tube and teflon dielectric combinations seem to take less time to break in and the less gap between conductors the faster the break in too. It seems to be a matter of the capacitance of the cable as related to AC impedience in the audio spectrum. A small charge builds up in the dielectric. If the cable has a low impedience (like Goertz or Nordost for example) it tends to have a very short break in period. If on the other hand it has a dielectric foam insulation and a relatively higher impedance and gap between conductors then the break in is longer. To my ears Audioquest type cables and others like them seem to have longer break in periods. The end results seem close in sound but cables with polystrene and nitrate foams seem to take 50 to 100 hours before they sound almost as good as a Nordost or Goertz out of the box. This is just my opinion and a little information gleaned from listening and reading specs. I hope that it is somewhat helpful.
Teflon foam or air tube and teflon dielectric combinations seem to take less time to break in and the less gap between conductors the faster the break in too. It seems to be a matter of the capacitance of the cable as related to AC impedience in the audio spectrum. A small charge builds up in the dielectric. If the cable has a low impedience (like Goertz or Nordost for example) it tends to have a very short break in period. If on the other hand it has a dielectric foam insulation and a relatively higher impedance and gap between conductors then the break in is longer. To my ears Audioquest type cables and others like them seem to have longer break in periods. The end results seem close in sound but cables with polystrene and nitrate foams seem to take 50 to 100 hours before they sound almost as good as a Nordost or Goertz out of the box. This is just my opinion and a little information gleaned from listening and reading specs. I hope that it is somewhat helpful.