99% of the time I press them to the side; I was told the reason for this was that over time the batting can sometimes come up thru the seams when pressed open. I don't know if this is true w/the batting we use today but why push fate. There are times that seams don't want to lay flat when pressed to one side and you need to do them open. I only do this when all the steam in the world isn't going to make them lay flat.