Almost never. I've never in my professional career had to invert a binary tree or write a sorting algorithm from scratch or reinvent a queue data structure. I've never had to build a Minesweeper clone or generate a maze. Any time I go into interviews and they ask me to do these kinds of tasks, I mentally roll my eyes and my excitement about the role drops.

I once interviewed at CrunchyRoll a couple of years ago, and every single interviewer asked me to implement some flavor of a tree traversal algorithm. The final guy mixed it up by asking me to solve the Knapsack Problem. At the end of the day, I said to the interviewer, "You must traverse trees a lot, then" and he looked at me like I was crazy and said "No, never."

Being a Netflix for anime company, I'm willing to bet they don't fill boxes/knapsacks with products, either.

Ok, so then WTF am I doing here?