I think it&#x27;s meant as a convenient &quot;rule of thumb&quot; in juxtaposition to the more commonly known &quot;10,000 hour rule&quot; (which also has some controversy[1]). They are just saying you can be pretty good at something with 2 less orders of magnitude than mastery.<p>1. <a href="http:&#x2F;&#x2F;www.fastcodesign.com&#x2F;3027564&#x2F;asides&#x2F;scientists-debunk-the-myth-that-10000-hours-of-practice-makes-you-an-expert" rel="nofollow">http:&#x2F;&#x2F;www.fastcodesign.com&#x2F;3027564&#x2F;asides&#x2F;scientists-debunk...</a>