Boss scolds hardworking employee for leaving work 1 minute before the workday ends, even though she comes in early every day

How much extra work is she going to get done in one minute?

Every office has its own etiquette for when employees should arrive and when they should leave. Generally speaking, if you're working a salaried, white-collar job, you're going to be afforded a bit more wiggle room regarding when you can leave the office. If you have a flight to catch at 7, and work ends at 6, your boss is probably not going to refuse to let you leave at 5. Depending on who they are, they might be a little bit annoyed that you have to leave early, but if you're generally a good employee who doesn't constantly leave work early for any little thing, they're not going to stop you from attending to your personal affairs every once in a while. 

Some offices are totally intolerant of their employees leaving for a couple of hours during their lunch break for a dentist appointment, which is so absurd. You only have to go to the dentist twice a year, and it takes less than an hour! Also, most dentist offices are not open outside of regular working hours, so when else are 9-5 employees supposed to go? Would employers rather their employees take work off to go to the doctor's office? That would guarantee they're doing less work than they would if they just took a long lunch break. 

If your office has a zero-tolerance policy for employees leaving before their shift is over, even if they're done with all of their work, you've got to respect it if you want to keep your job. The employee in this story is frustrated that her boss doesn't care that she comes in early, only that she leaves early.