rvs fan, when I have a block with that many pieces, especially HSTs, I press all my seams open. (The Quilt Police haven't come to my door yet). I find my block is flatter and I can match up the seams easier since the lines I'm trying to match are straight, not covered over by the seam allowance. I've also found it's easier to quilt without "bumping" up and down over seam allowances. Just my humble experience and opinion.