[blihp]

Building at least a minimal mental model takes me far less time than trying to jump in and code something without one. When writing a trivial method/function, it often takes only a fraction of a second[1], but having it tells me if I'm on track to accomplish what I set out to. The mental model helps you plan and course correct... without it, you're likely either learning/exploring/doodling (which should help you build a mental model) or flailing about. You can get by on smaller scale/solo projects without one but it becomes an issue if you are expected to work in/with one more teams and or larger scope/scale projects.

[1] It takes effort in the early years, but like anything else you work at it does become second nature. I often don't consciously decide to build a mental model for simple tasks... it just happens reflexively with minimal time and virtually no effort. Now the model may be crap/wrong... but that's the value if it: as soon as what you're doing/observing doesn't match the model, you know you have a problem and need to course correct.