Disagree 50%. Before you write any code (Corp World) you need a few diagrams detailing what and how you're going to build a thing. These lead to discussions and are refined/evolve into something you can start coding up.

Exanples -

https://www.wittenburg.co.uk/Work/Protection_System.aspx (insurance), and

https://www.wittenburg.co.uk/Work/payment_System_1.aspx (payments)