My hypothesis: read five authoritative books about a particular subject and you will have top decile familiarity with the topic.
A possible Pareto modification for the time-constrained: read one authoritative book, sufficient to identify, hire, and work with a competent, experienced practitioner in the field.
In other words, optimize for learning enough to be a good shopper and good manager of talent in the field. Sink time into doing rather than learning incrementally more.
For some endeavors, it’s important to internalize the knowledge. For most, though, it’s sufficient to develop adequate intellectual filters and then get to work and do the actual thing, preferably with input from others.
The A student in me wants to Learn All the Things. the rugged individualist in me says I should do it all by myself.