Divide and Conquer
Ten topics, in the order they build on each other. Get something wrong and it works out which rule you used, not just that the answer was off.
The route
This builds fluency, not exam technique
Drilling here makes the arithmetic and algebra automatic, which frees up thinking room in
the paper. It cannot mark your method, and method marks are most of a Cambridge paper. From
about three weeks out, timed past papers on paper matter more than this does.