Of course they don't believe you though. If you have any experience you cook those numbers to deal with people like them! I find fixed-length sprints harm agil

Of course they don't believe you though. If you have any experience you cook those numbers to deal with people like them! I find fixed-length sprints harm agile. You're tempted to suggest sprint-length goals, not the minimum useful product. This leads to distrust, because everything looks like estimate stuffing, yet you being honest intend to fill those days doing cleanup, automation, etc. All real work. And you resent every effort to trim even a minute. Usually even the surliest customer can be worked with by simply cutting them in on more of the planning (you do bill for meetings, right?) and letting them decide how far to push a "spike", etc. When they see their demands are heard and turned into work (and billed for!!) they often become much more open to suggestion, such as to stop beating an expensive dead horse. The goal is to be able to break down a project into functional goals (index the data, query it, script that, schedule that, add a GUI, etc.) After the first step or two you're producing value, on the way to the goal. One of the hardest problems in development is finding a competent customer for a PO, who can drive the project with requirements and political support. The more tangible you can make the benefits early on, the higher-level stakeholders you'll have access to and the less trouble you'll face getting things done.