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: 
Of course they are used in the industry. Just look at the Standard Template Library (STL)!

You definitely should know how to work with templates, and better, learn how to do some fancy things with them like template metaprogramming, ok, that may be optional, but template classes are not!

**EDIT:** Even more, a lot of other languages like Java and C# support the concept of generics, that being the equivalent to templates in c++, but generics are far more restrictive.
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.