The stuck place is earlier.
Find the missing link before you grind.
Find the earliest missing link before you grind the wrong chapter.
1
Name the stuck point
State the specific thing you cannot do, not the whole unit.
2
Prerequisite tree
List what it depends on, three levels down. (A1)
3
Probe from the bottom
One short diagnostic question per dependency, starting lowest. (A1)
4
Walk the chain aloud
Stop at the first link you cannot explain. (A23)
Prompt · Prerequisite diagnosis
I can't do [SPECIFIC THING]. Don't teach it to me. Instead:
1. list what it depends on, and what those depend on, three levels down;
2. give me ONE short diagnostic question for each, starting from the bottom;
3. wait for my answers;
4. tell me the lowest link I failed: that's what I actually need to fix.