I understand time constraints and end goals may prohibit the 'best' approach.
What I do not understand is how can you say something is more 'efficient' if the yield in understanding is less than what you would get with another method.
Hopefully this will clarify my thought process here:
If 'Best' is to teach others and requires 10,000 hours to yield 90-99% understanding.
In contrast, 'Efficient' method requires 2,500 hours to yield 30-40% understanding. However, there is diminishing returns meaning that doubling your hours to 5,000 does not return you with 60-80% understanding, rather maybe closer to 50-60% understanding. With 7,500 hours closer to 65-70% and 10,000 hours may around 75-89% understanding.
Here you've spent the same amount of time but did not achieve the same level of understanding. I think you may have a dynamic 'Best' vs 'Efficient' curve and to switch between those options to optimize maximizing your level of understanding in the least amount of time.