I used a clamp tightened around my base and left it on for approx. 8-10 minutes. It did stay engorged during the process, but it does not really thicken any more than when I tighten an “ok” grip around the base and squeeze and pressure toward the head for 20-30 seconds. Should I expect more from the clamp? Or does the 8-10 minues of extended engorgement lead toward girth more rapidly?