The 80/20 Rule Applies to Learning

In most skills, a small fraction of the material does most of the heavy lifting. The first 20% of concepts usually covers 80% of what you'll actually use. A beginner chef who masters knife skills, heat control, and seasoning can cook almost anything — the remaining techniques are refinements, not foundations.

This doesn't mean you should never go deeper. It means start with the high-leverage fundamentals and get them solid before chasing completeness. Learn the 200 most common words in a language before memorizing obscure grammar exceptions. Master the core before decorating the edges.