If you use any of the Adobe design / image applications, like Photoshop, Illustrator, or InDesign, and you do work for both digital and print use, then chances are you probably have to change units fairly often.
You may think you have to go into the preferences to change the units from Pixels to Inches, etc.., but there is a quicker way. All you have to do is right-click (or control-click) in the rulers of your open document, and select the new unit. If rulers aren’t showing, just hit Cmd + R (Mac) or Ctrl + R (PC) to toggle them on or off.