I don't really use poly primers to do that. In my experience, you will always be left with something if you do that, whether it be a tweak of a reflection or a low. I have learned if you skim it really tight with a clean spread it's not so tedious and then you can save that primer to help it give you a lazer sharp look. Just my opinion and I haven't used slicksnot or slick sand or whatever you call it.
Maybe inbetween is what's best... Just do one small skim past the lows and not two skims that I suggested and THEN hit it with the poly. Win win to me.