[roenxi]

As a counterpoint, it is impossible to discuss this topic without coming to some definition of "mastering" a tech stack. The concept itself seems suspicious. That is like saying "I mastered fashion". What, exactly, does it mean to master something that is in constant flux? How do we differentiate between a master and someone who read the documentation a few weeks ago?

It is a mug's game trying to master a tech stack anyway. The clever thing to do is master problem domains. Then if you encounter the problem you can just solve it using old tools and be happy.

[joshuanapoli]

Beyond some point, mastering "fundamentals" tends to look a bit like a barbershop pole. Engineering and computer science principles are in competition with each other. Within each tech stack, the balance of forces is different. It takes years of experience within a particular tech stack for an organization to find elegant and harmonious balance in techniques.