Scrum fails because rarely is it ever understood. 

I once worked in a team of 3 who all did the certified scrum master cert and were on fire for it. We did 2 software libraries over the course of 9 months and it was awesome. Then we split up to integrate with other teams. It was never the same again, people just want to keep doing what they always did and scrum becomes the scape goat. 

 My post wasn't really about Scrum but all the replies are. I guess I shouldn't have mentioned it at all.  I just wanted to highlight how often I find myself re-micro-prioritizing what I am doing, so often that no project manager could ever keep up in Jira [oh shit, now the replies will be about Jira]