Why cube-and-conquer works so good for CDCL?

[isPANN]

Metric	OB-SAT	march_cu	Ratio
Cubes	412–741	1894–3967	5× fewer
Avg cube size	~762 literals	~13 literals	59× larger
Decisions / cube	~1347	~167	8× harder
Conflicts / cube	~808	~124	6.5× more
Cubing time	5–13 s	1–2 s	5× slower

Total CDCL work:
OB-SAT = 1,445,559 vs march_cu = 893,115
OB-SAT does 1.62× MORE total CDCL work!