Feature delivery slows down the moment “we’ll figure it out in code” becomes the plan. Sprint planning starts falling apart when a design file only shows the happy path. The mockup looks clean and the flow makes sense, but no one has thought through what happens when things don’t follow the ideal scenario. Those decisions don’t disappear just because they weren’t designed. They get made later. Under deadline pressure. In different parts of the system, by different people. Over time, behavior diverges. The same flow starts acting slightly differently depending on context. It becomes harder to reason about, harder to explain, and harder to change without side effects. Six months later, teams aren’t iterating on the product anymore. They’re revisiting the same flow to untangle decisions that were never made upfront. This is how delivery slows down without anyone noticing it at first. Undefined logic moves the conversation from design to production, where mistakes cost 10x more.