System Design in a Hurry: Crucial concepts for system design interviews

One of the authors (Stefan) here. We created System Design in a Hurry after conducting hundreds of mock interviews and pinpointing areas where candidates tended to falter which could be fixed with some study. Happy to answer questions!

This is really clear and easy to understand. Probably the best one of these I've read while preparing. Can you add topk to the list of common problem breakdowns?