I think scrum and waterfall are both just procrastination. Instead of building the app, you do all this other stuff instead. Like when you clean your house instead of doing what you're supposed to be doing. Nobody wants to do real work, so productivity theater ensues. It's really all just productivity theater.

The most productive way is kanban because it's like sending orders to the kitchen in a restaurant. There's no due dates, here's the stuff that needs doing, just do it.