As a somewhat contrary opinion, personally I think that waterfall and UML are unfairly maligned most of the time. Waterfall can be an entirely valid management

As a somewhat contrary opinion, personally I think that waterfall and UML are unfairly maligned most of the time. Waterfall can be an entirely valid management approach. If you're working on a system that is too complex or ill-defined to be documented, maybe find someone who is better at systems design than you[1] or re-think the system boundaries and try to narrow its scope. Agile & co are just as difficult to pull off correctly if you have poor systems culture in your organization. [1] The impersonal you; I don't mean this as an attack