My experience is that they're not particularly useful. By trying to fit everything into two week windows, the team either overcommits and works harder than nece

My experience is that they're not particularly useful. By trying to fit everything into two week windows, the team either overcommits and works harder than necessary for no true reason and risks looking bad, or they undercommit and things that could be done today get delayed until the next sprint. That being said, my experience is that most teams start off being strict about sprint planning and boundaries, but over time back off more and more until sprints are a very abstract planning/check in every two weeks, which is fine. Just personal experience, YMMV.