"Slurry dulling" just means that on the vast majority of Coticules, the edge left by any amount of slurry on top of the stone, is not going to be sharp enough for a comfortable shave. If the slurry is thick enough, some Coticules won't even reach a shaving state at all.
Hence the need to always finish on water, maybe the odd stone in a blue moon not accounted, but even those will benefit from finishing on water.
There are 2 things that will speed up a Coticule (as any hone likely): Slurry and pressure. You can go overboard on both. When in doubt, always use less (thinner).
Dilution of slurry just serves to progress gradually from a fast action to the slower finishing stage on water. A while back, where we all still believed the word that was spread on a large shaving forum never to use any significant pressure for honing a razor, precise dilution was all we had to render a razor ready for finishing on water. But now that we have halfstrokes (or circles) and abandoned the idea that you may never use any pressure, you can replace a lot of that careful dilution by the application of pressure.
On a hollow ground razor, it is actually not only the augmented abrasive action that helps, but there is also a sort of tapeless Unicot effect going on. With pressure, the blade flexes a bit, which decreases the bevel angle a bit. During the final laps on water, the pressure is released. This releaves the tension releaved and the blade springs back on its very tip. Just like you would have applied a layer of tape to the spine. Because the bevel now rest primarily on the very tip, it gains that last bit of keenness without much problems.
Kind regards,
Bart.
