I like the hanging paper towel test also, a knife will do that good at 2k refinement... it's actually a rather good test to let you know if you've lost your teeth or not.
Sometimes when you get "up there" into higher grits, you'll lose the edge. It still seems sharp, cuts food decent, but it's just missing something, it probably means you lost your teeth. If your knife is above 2k, paper towel is a dead giveaway as to what's going on in the edge. If you've done things right, you should be able to slice a pinched, hanging paper towel at every grit from 2k to 16k, and beyond. What's a cool thing to do, if you like to deburr at each grit, just run the knife through a paper towel to both deburr and determine what's going on with your teeth-situation.
Every edge needs teeth, or it's not hitting on all 8 cylinders. Basically, you'll start finding out how to be more delicate at higher grits. As James Tiberius Bullman once said: "Slow and steady wins the race."
If you fly through the sharpening, and you lose the teeth, you'll have no clue what went wrong and when it went wrong.
Normally only a couple of things cause your teeth to fall off. One is raising the angle while sharpening, then not staying at that angle, aka Wobbling, and the other is doing too many edge trailing strokes on a swarf filled stone. A big one that is easily preventable is getting rid of your burr from the low grit stones. After 2 or 4k you shouldn't really have to deburr again.
As for sharpening with synthetics stones, I like to start with a slurry, sharpen until the slurry loads up with swarf and becomes black, then rinse the stone clean and do a few alternating edge leading strokes.. the "zoop zoop" method. This helps weaken any burr, but also "pushes" the carbides back into the blade, rather than ripping them out; Plus using a clean stone to finish prevents particles from running into the edge, giving you the best chance at a clean finish.