On the hexagons (OBW) I pressed all of my seams open, and they layed really flat, even after joining them all together.
Also a tip I learned on here :D have a small bowl of water near your pressing surface. Dip your finger in and place a drop of water on the center where all the seams meet, then press. Sometimes on the front side, too :wink: My hexagon blocks layed as flat or flatter than a 4 patch :D:D:D