"The prototype is nearly done." you're still pretty early in the project's lifecycle. software projects generally move fastest and have the least difficult cha

"The prototype is nearly done." you're still pretty early in the project's lifecycle. software projects generally move fastest and have the least difficult challenges early on, as a general rule, in my experience. once you have a lot of users, and legacy dependencies, and have to work right on N platforms, and handle edge cases, and be performant, and the codebase becomes so big you no longer remember all the details, and maybe a few years have passed since you were working on it full-time, etc., then you'll find that velocity and agility decreases.