Realistic cases are useful close to the interview when you use them to test performance, not to cram as many new case types as possible.

At that stage, the value is seeing whether your structure, math, communication, and synthesis hold together under realistic conditions. A completely new case can expose weaknesses that familiar drills may hide.

One realistic case might show that you are technically correct but too slow, or that your structure is fine but your final recommendation is not concise enough.

Choose a small number of good cases, run them under interview-like conditions, and review them deeply. If the interview is tomorrow, spend more time fixing the repeated mistakes than collecting additional cases. Keep a short note of what improved and what still broke so the next practice session has a clear purpose. Related CaseBasix guide: https://www.casebasix.com/pages/case-interview