It's rarely practical to start over from scratch. For example if other applications use the very same database, you can't just come up with a simpler database s

It's rarely practical to start over from scratch. For example if other applications use the very same database, you can't just come up with a simpler database schema. Also in my experience, many business applications aren't vastly complex, they are simply very big and have to handle many, many special cases. That's not something you can redo in a few weeks, no matter how talented and ambitious you are.