Hi D, I suspected that this factor might be brought up. It does seem obvious that it should be true in theory. However, I can't help but noting that virtually all cartridge manufacturers specify a recommended range for VTF that's wider -- oftentimes very much wider -- than the relatively narrow range I'm playing around within.
My takeaway is this: Even if the coil may not be perfectly centered in the magnetic gap, this fact in itself would pose no physical threat to record replay (as all manufacturers' specified ranges implicitly acknowledge). Since the 'perfect' setting is something I lack the tools to determine, and as you say is likely to change somewhat with conditions anyway, I can see no reason not to just go with the best or 'correct' setting being the one that sounds the best for any given record under the prevailing conditions (to me, in my system).
My takeaway is this: Even if the coil may not be perfectly centered in the magnetic gap, this fact in itself would pose no physical threat to record replay (as all manufacturers' specified ranges implicitly acknowledge). Since the 'perfect' setting is something I lack the tools to determine, and as you say is likely to change somewhat with conditions anyway, I can see no reason not to just go with the best or 'correct' setting being the one that sounds the best for any given record under the prevailing conditions (to me, in my system).