"Trying to talk a user through a procedure over the phone,"
Is the worst thing ever , it should be an absolute last resort , you should use every trick in the book before you try that. Remote control , mapping C$ and shoving stuff on , psexecing , pskill ,reboot ad infititum
I was recently working in earshot of the helpdesk and kept hearing one guy saying "its been 10 minutes now and we're still trying to enter your password" and silences followed by "Hello ? did you do that? what happened ? whats on the screen?"