Re: How much authentication is too much?
I also can't understand why you'd need to authenticate fifty times in a day. A number that makes more sense is "less than ten", for someone just starting up with installing their system. Of course, once you've settled down and are merely using your system instead of learning and setting up, you'll probably only type your password twice a day.
In any case, the authentication prompt is not so much to prove that you are the same person who was in front of the computer twenty seconds ago, but more of a way to ensure a piece of malware can't just invisibly make changes to your system. Access to modify system files and certain "privileged" operations is only available through 'sudo', 'gksudo' or Policykit, and all three of these require you to prove your humanity by typing your password. That's something a piece of malware can't guess, and there are systems in-place to ensure that malware can't actually overhear your password as you type it.
I try to treat the cause, not the symptom. I avoid the terminal in instructions, unless it's easier or necessary. My instructions will work within the Ubuntu system, instead of breaking or subverting it. Those are the three guarantees to the helpee.