When I do the pyramids, there is quite a bit of testing involved. Most of the testing occurs with my thumb pad, some of the testing occurs with my arm hair, and the final testing occurs with my facial hair. Now, that being said, on a razor that is NOT shaving and has just had a bevel reset, 1 aggressive pyramid IME will rarely put you in the shave test category. Quite often you'll be doing a conservative pyramid or two conservative pyramids following your aggressive.

Secondly, if you have a razor that is tugging quite badly you probably won't start at a 25/5 pyramid, but closer to the 10/5 and go on up. Practice helps with that assessment. It it's just started to tug, you'll probably do a conservative pyramid with a 1/5,3/5 sort of thing.

In terms of why it works, I think it provides a way to eliminate 4k scratches from the bevel without doing damage on the 8k side. When I was first learning on my Norton's one of the trickiest things was to determine when the edge "felt" ready on a stone, successively that is. The pyramid helps eliminate some of that guesswork at the start. It also helps to polish out those big 4k scratches when you don't quite know how many laps to do on the 8k to make that happen in the first place.

I think the pyramid works well with two razors. It gives you an opportunity to produce a shave ready edge fairly quickly (not time-wise, but learning-wise) on one razor and test for sharpness and comfort, while you work on the other razor using a successive grit honing method and a loupe to view your scratch pattern.

I mentioned in an earlier post that something neat to do is take out your 4k (just for fun), and do 3 or 4 circles on it. Now switch over to your 8k and do 3-4 straight laps on it. Did the scratch pattern begin to change? How many more 8k laps does it take for you to eliminate the 3-4 circles scratches on the 4k side? Also....if you want to see how it works another way: Find an old junker that has massive amounts of honewear. Run it on any stone without tape, and you'll see your scratch pattern in the flat honewear areas. Use a finer grit stone to see if you can change that pattern, and how long it takes to eliminate it.