Modifying Climbing Shoe Edge

I was watching this video youtube.com/watch?v=nK4JarY…
when around 2:09-2:16 I noticed Arnaud Petit cutting Alex Megos' shoe with a razor to end up with this

Nice screen shot grab!
They are speeding up the wear to gain more 'feel' from the toe.

As shoes wear, they reach a sweet spot, the sculpting is usually the result of a seasons worth of climbing leading to a custom fit.

Some times, way back when, people buffed or used a razor blade on the old rubber, (scale-ing) or scraping. This was before the better blends of sticky rubber came along.
He gets his shoes for free, so rather than climb on the thick rubber, they thin it down, shave it as you see.

I think he's trimming snagged edges so that they don't get worse and also to make the edge more consistent

He does the same in this video:
dpmclimbing.com/climbing-vi…
It is to clean up the shoe, remove any oxidized rubber, and reshape the edge. This will make the shoe climb better. Its basically a little preventive maintenance. Clean shoes are a priority for me. Check out this video too:
youtube.com/watch?v=ObtZPW3…