Range by David Epstein
This book takes the
10,000 hours rule
and turns it upside down as generalization builds success in many domains. Rather than early specialization ala golfer Tiger Woods, Epstein promotes breadth ala Roger Federer who dabbled in many sports before choosing tennis.
Chapter 4 (Learning, Fast and Slow) outlines the the benefits of mixed Math practice rather than just one type of problem as described in
Epstein encourages readers to broaden their horizons with "the most impactful inventors crossed domains rather than deepen their knowledge in a single area." and encourages range with "people who think broadly and embrace diverse experiences and perspectives will increasingly thrive".