[ozmbie]

I agree that sprint lengths can be arbitrary and counter-productive to developing good software.

I think it's important to understand that the sprint "membrane" is not designed to help developers. It's designed as a compromise between developers and their managers.

Developers want to work uninterrupted and perfect their work before releasing it, and managers want working software quickly and like to interrupt developers and change courses frequently. Sprints are an attempt to find a middle ground, but it's not always ideal.