Most of this type of rulers definitely need careful pressing with Best Press or Starch as you sew on the bias.
I tend to use either The Angler 2 when I have some HST's I want to make. For larger numbers I use Thangles. One of my best quilting buddies got a ruler from That Quilt Patch HST ruler. It also makes great QST's and combinations. I am tending to think of getting that ruler when I have a need.