Last time I used a whiteboard was when I was re-architecting some classes and I mapped out the class and function names and how they interacted with each other.

Last time I used a whiteboard was when I was re-architecting some classes and I mapped out the class and function names and how they interacted with each other. This enabled me to see what changes I would need to make/add to get the desired effect. The time before that was for a database migration where I mapped out each step that had to be done and in which order.