I took a workshop from Mary Ellen Hopkins, a quilter from Santa Monica, CA who was at the forefront of the machine piecing movement back when it wasn't popular to use your machine for anything except sewing binding on. She encouraged us to leave them open. It takes way too much of our valuable time to open & close them any more than necessary. I store my pins in a round Singer tin lunchbox. I have about 3000 as I pin heavily. Yes. sometimes I get gently stuck, but what I do is grab a pin which usually brings a bunch with it. I move my hand over the quilt and gently shake the pins loose as I move over the quilt. This distributes them to where I will use them.
I USE A KWIK KLIP to aid the closing of all the pins. I love it & worth the investment.