I have been chasing the "liquid mercury" edge for a long time.
The fundamental secret is your very first stone.
Here you need to make damn sure that the bevel has been perfectly set/profiled in all aspects.
Also your final couple of strokes on your first stone must get progressively lighter & lighter until just the weight of the stone arm is working.
The above is very important - because as you move up with the finer grits, you loose "grinding" performance with each finer stone you use.
After your first stone, all subsequent stones are just "polishing" out the scratch pattern, NOT performing any real profiling/grinding, therefor many strokes at extreme light pressure is the way forward.
It is purely a time/patience based exercise.
The first most common mistake was trying to grind out spots on the blade with finer stones, because my first stone was not perfectly finished.
Second most common error relates to stone flatness (especially when spritzing with poly diamond) - the stone wears very much faster and the resultant stone dishing presents a problem for the next "flat" stone in relation to consistent 100% full bevel contact - do not get carried away on one side of the blade every time you start a fresh stone - do like 2 passes & flip the blade (repeat) - this way you ensure more even contact between stone & bevel before the stone dishes on just one blade side.
I sometimes lap my stones twice during a "mirror" session for one knife.
Third common mistake - maintain & repeat EXACT blade position on the blade table - not doing this results in different contact areas on the blade which puts you back to common mistake one.
Fourth common mistake is tolerance levels/play/precision in the actual equipment - eliminate it if at all possible - use the drill stop collar/angle cube & angle degree upgrade arm.
Lastly, take your time - put your heart in it - CONCENTRATE ON EACH stroke!
I am still practicing to achieve that ultimate, perfect mirror bevel - it is a slow process though......