Be organized and diligent.
Track what you are doing and figure out what's missing.
For example, I give my coachees a casing matrix, which is basically industry vs case type, and allows them to figure out if they have yet to practice a particular type of case / industry (and allows them to kill two birds with one stone, but finding a case that has both a case type and an industry they haven't done)
Another example is tracking your casing strength across the key criteria (i.e. math, critical thinking, communication, etc). Knowing where you're still weak will help you focus on the important areas.
^These are two examples but there are more.
I highly recommend you book time with a coach if you truly want "high quality, low volume" practice. They will give you the biggest bang for your buck not just in terms of that hour session, but in directing you well for all of your future independent practice. Coaches truly are a lever!