Tennant expresses this point as "Learn only what is required to accomplish the task before you." As much as I agree, I think this could easily be misinterpreted. A few caveats:
- As one commenter has already pointed out, this means learning enough to know what you are doing, even though you won't explore all the details of whatever tool you're working with. If you learn just enough to know where to apply duct tape and rubber bands, your future self may hate you for it.
- Some skills and technologies are useful to learn even if you don't have an immediate need. Either you're certain to need the skill or knowledge eventually anyway, and/or learning it will help develop ways of approaching problems that will help even if you're using a different tool. Probably everyone has a different idea of what these fundamentals are, and they will change over time, but would anyone disagree that some skills are fundamental?
- It doesn't hurt to learn about things even if you don't have a need to actually learn them. Having an idea of the possibilities will make you better prepared to face a new problem or to reconsider the way you do things.