Question: I'm new to C++ and am wondering how much time I should invest in learning how to implement template classes. Are they widely used in industry, or is this something I should move through quickly?

Answer: 
At my employer, the **main** thing we use that's in C++ and not in C is indeed generics, AKA "templates". Inheritance &c are nice (but with pluses and minuses), but templates are *absolutely crucial* -- **the** main, cost-less advantage of C++ over plain C. Master them, you **won't** be wasting time!-)
No, don't spend to much time on learning how to **implement** them. The other answers correctly explain that you certainly should learn how to *use* them. That makes sense; many libraries provide class templates and you should be learn to use those libraries. But writing your own templates is much rarer.