I'm still a beginner, having honed about 20 or so razors. But they've all turned out well. I have been very careful about what I actually try to hone, so I credit the good outcome to the folks at Solingen and Sheffield!
I use the TPT at the bevel-setting stage, since I have a pretty good sense of what a wicked-sharp knife feels like on my thumbpad and the TNT for seeing how the edge is coming up.
I had not heard of the TPT for testing shave-readiness, though. I usually drop any tests except hair-cutting (arm and leg hair) once the bevel seems set.
Does anyone else use the TPT for shave-readiness? Is there a chance the TPT could potentially harm the very fine shaving edge of a razor coming off the finishing hones?