I do a fair amount of sewing from patterns (clothes, etc.) and never use more than two pins per pattern piece. Those are used to keep the piece on the fabric grain and I usually pin right through the grain "arrow."
After that, it's pattern weights. You only need one set as that's about all the room you have to spread anyway - the garment length, width, etc.
In fact, I was thinking of doing up some nice shapes of something, filling them with birdseed (nice weighting in that), and setting them out in a basket for display when not in use.