1 as noted different grinds etc all add to different feels
2 The good old Sheffield vs Solingen steel comes into debate again
3 I think 90% of my flipping motion is done with the thumb alone rolling on the bottom of the tang and the rest is a slight wrist roll to get all the way
A definate must practice and try perfect as you could have rolled your edge or just not stropping the edge enough
4 if your stropping technique is out it will reflect with the spray or paste etc also as you will only be polishing the spine not the edge if you are not rotating enough