implements by architecture.
Even if you have an architectural phase, it's worth implementing by feature, implementing only what you need in the architecture for each feature, and integrating as you proceed. If you implement by feature and integrate as each little piece works (several times a day, or at least once a day), you have continuous integration. Continuous integration provides you immediate feedback about your or your team's progress, which eliminates 90 Percent Done.
Project managers have several ways to stop 90 Percent Done or even eliminate it entirely. If you don't stop 90 Percent Done, you'll end up with a death-march project-and no one wants that. Knowing your real status frees you and the team to make great decisions and not have a project that doesn't end because you're caught in the 90 Percent Done schedule game.