I recently touched up a blade after 13 shaves because it seemed like it was a bit less keen and I was curious if my ark could bring it back as I definitely find it rather slow and subtle (but also really like how that lets me tune up my coticule edges a bit while still leaving them feeling coti-ish). Definitely noticed a difference so it does something :)

But for the most part I have too many razors to get them that far. However I do wind up re-honing them when, for various reasons, they don’t retain an edge. Sometimes the steel is too soft for the bevel angle so I need tape to make it a bit more obtuse and get reasonable edge retention (usually in these cases it degrades over the course of the very first shave on the edge). That could be because previous honing has taken too much off the spine or the steel is somehow compromised eg. by polishing or regrinding done carelessly allowing the razor to get too hot and affect the temper. Beyond changing the angle I also find one can get lucky and just need to take off a bit more metal, I wonder if some of those weren’t necessarily heat treating but some subtle oxidation or something over time that affects just the thin layer near the very edge so even if I’m lucky enough to find an old razor without any pitting or damage to hone through I might need to take off a bit more than it looks like.

I imagine similar things (steel hardness/quality, bevel angle) can also affect the overall edge retention so even with my same face and technique some of my razors with hard steel can probably go for 20 shaves (if I ever let them) while others would not be able to hold an edge past 10.