HTML is one thing, most of it comes down to logic, and knowing things about architecture, and syntax. HTML and the web is imperfect and needs some help, the foundations are bad. I learned to code in assembler and then worked in C and Fortran. Some of this is by repetition and I likely am faster than most programmers, I can type fast. And my visualization is fast since I can abstract and then code things quickly. It gets harder since I do kernel code and drivers and do things which are not monolithic, as in they need to preempt and be concurrent with other threads of execution. You need to know the paradigms and the traps. I am self taught mostly.