Having to much pressure on the nozzle will cause it to wear down faster, but a good needle will not get a ridge line due to the softness of the nozzle.
When I did mine I have it set up when the nozzle had hardly any force on it and was mainly going to see it I could make a matched set.
When you read about the Micron , It is suppose to have a matched head system , To me that means that the head and the needle are match at the factory. So being a gear head I figured I would give it a go . I did use a needle and nozzle that had given me problems off the Eclipse CS, Being I had a brand new set to go in if it did not work out. But that brand new set is still in the package cause so far (2.5 years now) the set I lapped is working great.
But not something I will suggest just anyone to go try . It is like polishing a needle if you get it right paint flows great if you screw it up well you get to buy a new needle.