Mini Case Interviews? Any good resources? Advice?

Coming up on a 2nd round interview with multiple 30 min interviews consisting of mini case questions. 1st round consisted of entering a new market and market sizing/back of the envelope questions (all less than 15 min). Anyone know any good resources for practice case questions that are less than 30 min long?

This isn't for consulting per se, but the questions are like shortened versions of management consulting case questions. I've read Case in Point and looked through some case books but I don't want to waste my time trying to tackle cases that are too difficult when I can master the mini ones I need. I've got a week to prep; any resources would help!!

tl;dr
Looking for practice mini case questions