The four most important words in coaching are "Shit, this ain't working!".
Again, reflecting on my year in South Tama I think this phrase is one that I used quite often! It's also one that I think is important for any coach - you have to be able to admit to yourself that what you are doing isn't working. You need to be constantly analyzing what isn't working, and more importantly you have to figure out why. There are a lot of coaches who will stick with the same thing even if it's gone far south.
Now I'm not saying if your motion isn't working that you go to the flex! What I am saying is that you need to admit what you are doing isn't working and figure out how to tweak it to make it work. For example, in my year at South Tama, I tired to start teaching the motion by teaching the drive and kick aspect first. I quickly discovered that action was not what fit the players. So instead I started to teach pass and cut, backdoor, and screening actions. I didn't abandon the motion offense, but I did abandon the motion concepts I was trying to teach.