Meh...as AD pointed out, the process gets very frustrating on our end. No matter how good your professors are, and how much they guide you--and, trust me, mine did--no one really tells you how to go about a dissertation topic, how to write a proposal, what some of the easier routes are to get to your topic and data, how to lay out the dissertation. These are all things one has to do themselves...and if you don't know what questions to ask, you end up taking longer than you probably should. Don't get me wrong, I am excited about my topic and my writing, and I have a type-written list of 3 pages of various future research topics; but after 3 years of finding out what data I could find, finding data, analyzing data, and re-writing my chapters over and over again, I'm not just burnt, but charred. What makes matters more tiring is trying to find a full-time, tenure-track teaching position at the same time as all the editing mess...and not finding much out there. It's a lot of stress, but in the end, that fancy title will be worth it!
The process here in the States is usually:
1) 2-3 years of coursework--depends on what your Masters is in, where you did it, etc.;
2) PhD Comprehensive exams--just to prove that you know what you know, and that you should go onto a dissertation;
3) Candidacy, which starts once you put in your dissertation proposal.
"In theory," you should take 2-4 years for researching, writing, and defending your dissertation. Reality is that, if you do not have a dissertation advisor (or, in some cases 2 advisors) who takes interest in you, and keeps asking about your work, it could drag on for YEARS. I have heard horror stories out of English and History departments where people have taken 10 years total, or more, because their committee never asked about their work, never gave them feedback, and they kept changing their topics. While graduate programs do accept more and more students into the fold, after a certain point most universities lose money on PhD students, and they don't want ABD's (All But Dissertation students) to languish in the system.