The HHT is only marginally useful *after* you finish polishing your edge. On a 1K or 4K edge, the hair can wedge into v-shaped notches/scratches in the edge from the coarser grit hones and depending on the particular hair you are using, they may catch easily and break, giving the impression that the edge is sharp, when in fact it's just rough.

I never use the HHT as my hair simply won't work for that purpose. I do find using my "moustache" test, lets me know when the edge catches hair instantly and the amount of tugging lets me know how polished the edge is. I just lightly brush my moustache with the edge in a shaving motion. If the edge is really keen, it catches no matter the angle. When I cut a few of the moustache hairs, I can feel how easy the edge cuts through the hair. It's still not a perfect test, only the shave test matters.

All these types of tests need to be calibrated by the individual and in the end just give you an idea of where the edge is at. As you noticed, you got faulty information from the HHT off the 1K and 4K, so that shows it's not a valid test for you. Perhaps some other test will work better, such as the thumb pad test or...... I can't tell you what to use, only you can figure out what does work for you. If your hones are reasonable flat and your honing is reasonable consistent, there is no way your razor will get duller when you move up in grit, but it will show that you have not done sufficient work on the previous coarser hone.

You might want to have a look at the 1K shave thread..... Once you can shave off the 1K hone, moving up the grit ladder is quite simple, just remove the scratches from the previous hone and you're done.

Regards

Christian