Feynman is not talking about just "turning the crank" as it were, but actual deep intuitive understanding of the 'why'. I agree with you that after you know ho

Feynman is not talking about just "turning the crank" as it were, but actual deep intuitive understanding of the 'why'. I agree with you that after you know how to setup the system you want to analyse, turning the mathematical crank can be straightforward and sometimes not so interesting.