Pithor you have touched on something I believe with all my heart, although technique, stropping(the most important aspect) prep and ones own beard play a big roll in how long and edge lasts. But in our quest for the ultimate edge, we keep getting that edge so fine it has no strength. I noticed from my own tests that once I could get a very nice edge from an 8k Be it synthetic or Coticule equivalent, it was an edge that would shave well longer than one off of a 12k and even longer than the 20k.

No to the OP remember more laps n the strop doesn't help unless they are good laps, cause 20 laps bad are even worse at 100 laps. Stropping takes some time to master, and when you do you will be able to improve an edge. Also if you have a junk razor 9 shaves might fe all you could get. I personally have a tough beard and shave everyday, I can go for months with just a strop, I don't but can. I adopted a maintenance routine that keeps my razor shaving with a couple or four laps on a 12k every 14 or so shaves. Tc