Back in 2011, I identified some of the reasons why I was considering starting a PhD:
My hope is that I would be able to do my research on something of practical importance, and that I could do useful work of my own at the same time as the doctoral program was progressing. It would certainly be pleasant to get back into a university environment.
So far, I haven’t done much research within the PhD program, aside from the limited sort that is necessary for assignments. I have devoted a pretty good amount of time to outside projects of my own – particularly Toronto350.org and photography. In fact, the enormous amount of difficulty I have been having with my first comprehensive exam is probably reflective of the degree to which I can muster a lot more enthusiasm for that sort of work than I can for undertaking a comprehensive review of the political science literature, including in areas of little interest to me and to my intended research topic.
After two years in a PhD program, it seems fair to say that if your only obligations are coursework and teaching, it is possible to devote a fair amount of time to outside projects of our own. Once comprehensive exams come up, however, that becomes far less possible. Furthermore, if you have any intention of getting an academic job, you probably need to be devoting nearly all your time to PhD work, including cultivating relationships within your department, getting papers published, attending conferences, and all the related work of building the scaffolding for an academic career.