What about review? Code review? QA? Showing off to stakeholders? These things add a delay, and there is a 'crunch' around the end of sprints where things are artificially urgent. I am not sure that is optimal. I have not heard a reasonable solution to this, other than abandon sprints maybe?
I think this stuff works wonders when at MVP stage and number of users < 10 maybe. For mature and complex products, the type I typically have worked on it is not ideal.