I have done everything from fully polishing every moving part, to just the bare minimum.
in this regard (trigger mech, trigger relay bar, etc) it is easiest to polish only the parts that have metal on metal contact. so in short, YES, the part where it moves in the trigger mech, and at a minimum the right side of the bar (when looking at it installed, against the frame)
of course lubricating these points as well will maximize free movement.
also, i prefer to lubricate with the following: (this is for real steel, yet i find it WONDERFUL for many other things.....
http://www.corrosionx.com/corrosionx-for-guns.html
