I guess no one would argue for decomposing use cases, that is just wrong. However sometimes it is necessary to specify use cases, which are on lower, more technical level, like for example authetication and authorization, which give the actor value, but are further from his business needs. Cockburn argues for levels when needed and explains how to move use cases from/to different levels and how to determine the right level. On the other hand, e.g. Bittner argues against use case levels, although he uses subflows and at the end of his book mentions, that at least two levels areneeded most of the time. My questionis, do you find use case levels necessary, helpful or unwanted? What are the reasons? Am I misssing some important arguments?