it depends on the pattern/seam i am working on- if i want my seams to 'nest' i press so they will- often this does mean toward the dark-but not always- if dealing with lots of bulk- pressing open at times is the better way to go-
there are no -- hard rules---you press the way it works for what you are working on- some patterns tell you which way is best for your pattern- sometimes you have to figure out for yourself what is the best.---no reason for any 'conflict'