Quote Originally Posted by matt321 View Post
...
Maybe I'm not staying on the 4k or 8k long enough? How do you know when to move on from those?
When the scratch pattern from the 2k has been largely replaced by a 4k or 8k pattern. Often visible in good light without magnification. Or when the TPT and/or HHT gets noticeably better. Or all 3.

I use the visual method until it looks close finish-wise. Then I TPT the edge. If the TPT confirms my visual assessment, then I'm done on that grit.