Not to mention, I strongly suspect that within the current educational system, the limiting factor is conscientiousness, not IQ. (At least, for high school and most undergraduate systems).
You are right, instead of focusing on teaching integration better, focusing on teaching conscientiousness might be the better goal.
Assuming that it can be taught. It's possible that the key components that link conscientiousness to academic success are prefrontal/ventral tegmental stuff such as different reward mechanisms (motivation, willpower) and differences in executive function (attention and inhibitory control), and we don't know to what extent teaching can modify that. Executive function, at least, seems difficult to alter via training.
Plus, we'd have to separate out the components of conscientiousness though - it's possible that conscientiousness is not entirely positive. Cons...
The soon-to-be-resigning Dominic Cummings, advisor to the Education Secretary of the Coalition government, has released a 250-page manifesto describing the problems of the British educational establishment ("the blob" in Whitehall parlance) and offering solutions. I post this here because both his analysis and recommendations are likely to be interesting to LW, in particular an increased emphasis on STEM, broader knowledge of the limits of human reasoning and how they relate to managing complex systems, an appreciation for "agenty"-ness in organizational leadership, whole-brain emulation, intelligence enhancement, recursive self-improving AGI, analysis of human interactions on a firm evolutionary-psychological basis, and a rejection of fashionable pseudoscientific theories of psychology and society. Relevant extracts: