There's down time in virtually every job. If your employer discourages you from using down time to get better at your job, then get a new job. I did it even back in college working at a chain pizza store. I learned some management tasks, how to proof dough properly, etc. I'm sure there's some jobs out there where it's not an option, but I feel like you guys are really stretching it to find ways to say people are incapable of self improvement at work.