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: 
In addition to what the others said, they can be incredibly useful in your own code, and you definitely will come across it while reading others', so there is no harm in learning it.
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.