First 2 Interviews in one week- HELP!

A recruiter reached out to me one week ago and I’m having the first 2 interviews next week and if successful the other two the week after.

I won’t have time to do 100 cases, so how can I efficiently prepare for the case study. Are the ones from their website good enough? I feel they are very easy and not very in depth.

Any tips are appreciated, thanks 🙏🏼
It’s for their procurement service line - operations in Germany