NEVER LOW OR HIGH PASS......
unless it's needed.
it ends up being 'unnecessary' math you are doing to the digital wave files.......
AND
if you are not using LINEAR PHASE ACCURATE EQ'S.....
then you may very well be adding phase problems and artifacts to your mix that you do not want.
that said.......
i DO use low pass on any tracks that i did not get right to start with.
and i always end up tweaking mids and highs on almost every track.
but i use a nice EQ (Waves Linear Phase EQ) on sub busses, and will use the SONITUS eq (remember, i'm on Sonar 6PE) to add color to things i want to tweak, but usually only subtractive eq.