I once built an anchor consisting of two t-slotted pickets and one vertically driven picket. Justin, do you remember this? I was belaying a folower up (not Justin) and they fell twice, the second time taking a pretty big pendulum. The anchors did not budge, but then I spent a lot of time and thought on how I dug the trenches and how I placed the driven picket. I didn't love the experience, and three pickets is definitly not my first choice for an anchor. But the belay was solid.