Everyone uses Photoshop differently, it is one of the great things about a well designed tool. I love showing a new Photoshop user a few basic tricks and watching them tackle problems in completely unique ways.
Spot colors can be a super useful tool, especially as a cost saving device for the customer.
Everyone suddenly has a lot of opinions about fonts. It used to be designers and artists trashing Comic Sans and Bradley Hand, after a few years Helvetica had a pop culture following. People got tattoos, it was serious.
So you inherited a file with thousands of high res jpegs that need to be resized for web use, great. You could spend the week mindlessly resizing them one by one, or do it once and have Photoshop do the rest of them.
Ever print something that had a large black graphic that looked terrific on your screen but dull and grey on the print out? Time to learn about Rich Black, or how to get your darks their darkest.