The surah with the most mistakes is not always your weakest surah in an absolute sense. Sometimes it is simply the one being stress-tested most honestly.
That is why error data should not be read as shame. It should be read as diagnosis.
When one surah keeps surfacing, the answer is usually not "repeat the whole thing more." It is to ask what kind of weakness is showing up.
Is the problem sequence, mutashabihat, weak transitions, overloaded verse groups, or an underbuilt mindmap? Once the weakness is named, the fix becomes much more targeted.