I honestly can't tell you how many case management systems or CRMs I have built from the ground up, or mostly ground up over the years. And if I had just built one, and then was asked to rebuild that same project to the same, or mostly the same specs each time, I could establish a nice factory with +/- 5% variance or maybe even 1% at this point on timeline, quality, and budget.

Except... no one has ever asked me to build the same thing twice, or close to it. Even basic stuff like "I want a password reset system on my login page" is often different from project-to-project!

The apps that can be done factory-line style are the basic internal apps... things like regulatory compliance... where someone just needs a bunch of basic list and detail screens with not much design and little smarts, because the app is NOT a differentiating factor, it's just a checkbox. Like the app to record when equipment was last calibrated, or the app to log that the security guard made their rounds as-expected. That's where you can apply factory line thinking to software development. As soon as it's mission critical or has any secret sauce, that's out the window.

J.Ja