Interactive debugging. "Most bugs are a result of the execution state not being exactly what you think it is" (Carmack) and it's astonishing how many people jus

Interactive debugging. "Most bugs are a result of the execution state not being exactly what you think it is" (Carmack) and it's astonishing how many people just refuses to effectively debug using an interactive debugger, which allows for easy inspection of anything, at any moment, with a REPL for a given state of your program, including call stack inspection/jumping and what not. Some say that "printing" and/or "logging" is just "enough", when those are other debugging techniques and often needed too. Heck, even some say that "if you need to step through your code you already are in bad shit" just as an excuse. Knowing how to do effective, interactive debugging in any language is a major step in productivity: it helps in so many ways: learning, diagnose, getting things done...