One of the oldest concepts of doing a PhD is that you need to "do your time". It's a tradition. Why should any professor want to let students get get through without doing what they had to put up with? However my supervisor's goal is to build an empire, unfortunately that needs to be done with labor, which means lot of students. Honestly, if I had known this I would have chosen a different advisor because I see a difference between doing your time and being cheap labor. To me "doing your time" means something is being learned that has to do with research, no matter how menial it is.
My supervisor has high hopes for himself. He wants buildings named after him, but to do that he needs prestige. How to build prestige better than fame. What if you don't have fame? Then you fake it. He holds multiple conferences throughout the year for the different research groups he is in charge of. With all the conferences he uses the PhD students to staff and run them. I have no problem helping with a conference that has to do with my research area but it helps no one for me to be filling envelopes for a conference that has nothing to do with my research. The PhD students are seen as cheap labor. Usually in exchange for this we get to network with the people at the conference but instead we are moving flags around to different entrances to save money and filling seats when he or donors give talks to make it look like there are more people attending the conference. I have not been able to talk to anyone other than other PhD students.
I by no means am saying that he expects only the students to do work. He is always working. Since so much of time was spent working on conferences doing normal research needed to be done during the holiday break. The problem was that my supervisor tasked me with creating an Intranet over the break instead of hiring an expert. He had chosen software to run that I was not familiar with and proved more complicated and time consuming. I used the entire break learning the software and building the site to his specifications. I ended up getting revisions to complete the next day on Christmas eve and New Year's eve at 11:45. I was able to launch the site after the break but at the expense of getting no research done.