It is all just preference. I either press to one side or spin my centers (esp if there is a lot of bulk at the intersections). I press row 1 one way and row 2 the other. Nest my seams sew the rows tog. I then make a call as to how bulky the seams are. If I think they are too bulky I swirl them if not I press them in one direction. I rarely will press an entire seam open (I do occasionally press short internal seams in a block open to reduce bulk). - My opinion (and I know that others will disagree) lots of seams pressed open are a weakness in the quilt.