The thing about Scrum is the observations and principles make sense, but then to sell it as a course they've turned it into very specific prescriptions. I went on a scrum course and the takeaway was basically that feedback is a big deal, and you should try to get some repeatedly and quickly. It's also common sense that you should have tasks written down somewhere, and that some of them are more important than others.…
The problem with any system is that people try to enforce it, military style. In my previous job, we did scrum, but not too strict. We had two week cycles, not-too-strict deadlines (most of the time) etc. If I finished my task early, I was free to pick up tasks from the planned list, without having to get permission from my manager. We also didn't agonize over story points, retrospective etc. We did it light hearted…
This is a thing that's pretty key to Scrum: velocity can't be used to compare teams. It is easy to misuse though. I would start every meeting I were in with "these points measures cannot be used to measure performance between teams."