There are no Rules!
So, rule number one (for me): if it is over six inches, pin it to keep it where it belongs (sometimes :-) ).
Easing in fullness: pin the ends then pin the rest as you think you need to.
Borders are always pinned (for me).
Matching points: I can't get a point to match reliably if I don't pin (always).
Well, those are the rules that aren't rules :shock: