The point of figure 4 is to admit that the neat step-to-step iterations in fig. 3 don't always happens. Sometimes testing reveals flaws that are bigger than th

The point of figure 4 is to admit that the neat step-to-step iterations in fig. 3 don't always happens. Sometimes testing reveals flaws that are bigger than the preceding coding step, and you have to back up to design or even requirements. But then once you back up, you still have to go through the remaining steps without skipping them. Ex: Testing reveals a corner-case that was never accounted for in the design. You can't just re-code, you have to go back up and redesign, then code the new design, then retest. Royce's recommendations to minimize these problems are a) more and better design, and b) more and better documentation In contrast, the Agile approach is to try to slice the work into finer and finer tasks, so these same activities can span a few sprints. It works in the small, but loses the forest for the trees.