My gut feeling is that it all plays a part. If you , James, were to take some extra time and do a really through prep I would be interested to know if you noticed a difference in how the shave felt and if it turned out to be closer than what you routinely do now.

As far as edge longevity the steel type, temper, grind and all of that undoubtedly plays a part but what it is cutting and how it is maintained afterwards must also be an important part of the equation IMHO.