They were using a large number of small struts, a few hundred per rocket. The problem with redundancy through quantity is that occasionally one of those many re

They were using a large number of small struts, a few hundred per rocket. The problem with redundancy through quantity is that occasionally one of those many redundant parts will fail in an interesting way, like happened here, and cause that one in a million cascade. The trick is finding just the right amount of redundancy for the task at hand. Sometimes that's a few strong pieces, sometimes it's a lot of little pieces.