after the 4K, I only use the TPT sparingly while on the 8K, and what I have noticed is that as the blade gets keener (sharper), it starts feeling less sharp, or at least less of what you would intuit as sharp. It feels almost glassy smooth, and the only reason you would know its "sharp" is becasue the bite is more agressive, i.e. the blade will cut deeper with less of the blade.
For example, at the end of the 4K, the balde will feel smooth to the thumb pad, and as you oull it across, you may get 1/2 to 3/4 of the way across the blade and go "who! this might be cutting deep, I better back off!". Once you get through the 8K, the amount of smoothness on the edge of the balde is barely noticeable, however, the bit is more agressive, and with the SLIGHTEST amount of pressure, as you pull the blad will sink in alot quicker, so you may get ony 1/4 of the way across the blade with your thumb pad and think, "wow! this is cutting alot quicker"......
Sorry, it makes sense in my head, but its hard to explain. Just another thing I have noticed. But yes, I agree. once you are past the 4K, I find the thumb pad less helpful, and found myself relying soly on what it did to my arm hair.

Basically, the jist of it is, with all the tests, skin and hair are different from one person to the next, so its hard/impossible to say exactly how a blade will/should act at a certain stage of honing. The best thing is to test the whole edge frequently during the process, in various ways, and TAKE NOTE of the results. If it seems to be getting sharper, you are doing it right. If it seems to be getting more dull, you have made an error somewhere. try to figure out what that error was, backtrack, and try not to do it again.