VH -where to begin .. My experience is not so much with graduate school as a participant, but rather as an observer, having had a largely different experience from yours in a European University.
Sadly your report of the worst type of Graduate School experience is likely mirrored, in whole or part, by that of others who worked toward an advanced degree at a US College or research University. There may be some, I am sure, who will report an experience quite different from that through which you suffered. I suspect that the biggest problem emanates from you primary advisor's lack of flexibility and imagination. But, in my opinion the issues that exist in the structure of graduate school in the US demand (and have demanded for a great length of time) significant improvement. Personally, I found the worst excesses of the graduate school process in the US utterly appalling. I thanked heaven that I was not directly exposed to the same as a GS.
The underlying problems with US based graduate schools (in the sciences and engineering at least) have more than one facet. It is part structural, part institutional and part cultural. The rest of the experience is dictated by that most fickle of variables, the human factor.
The structural component is caused, in my view, by the exceptional breadth of experience and capabilities that each individual graduate student brings into a particular graduate school. There is almost no common ground, no firm basis for measuring your capability against that of your cohort. This happens because each source institution from which the entering graduate student arrives may have a radically different syllabus from your own.
How does that range of capability and scholastic achievement tie-in to the high pressure graduate school experience you describe? It fosters an environment where the goal is to test the incoming class and, in a Darwinian manner, weed out the weaker students. One means by which this is accomplished is to force entering graduate students to take a large number of advanced level courses. Ostensibly, this is done to bring all the graduate cohort up to a level playing field. While that goal can be accomplished, it also sets up a situation wherein the graduate student's rate of progress can be used as a hammer against their future progress in the institution. Some of those advanced level courses have to be delivered by Professors that also hold power over the student's future prospects for assignment of research projects. As a result, it can arise that a Professor will force a student, with an interest in a research area in which the Professor specializes, to take courses that are of too high a level - perhaps to simply fill out a class.
The above also leads to institutional issues that directly impact the quality of the graduate students experience. One consequence of the advanced course curriculum is that it takes away from the Professor's time and his ability to deliver courses to the undergraduate body. As a result it is often TAs and graduate students that pick up this slack. That does nothing to enable the graduate students own progress in their chosen area of research. It is reasonable to demand that a graduate student contribute to the teaching of others, that can be a valuable experience in and of itself. In fact in Europe such lab or classroom setting teaching is an expected duty (in the Sciences or Engineering at least), but the quantity of such work is carefully metered. Where this goes awry is when it becomes a dominant activity. Sadly, that, in my experience could happen all too often at US Universities. If you are spending more than 15 hours in teaching or other extraneous duties it is simply too much. Once through those advanced level courses your dominant activity should be the chosen area of research.
Perhaps cultural aspects affect this difference. In a European setting the incoming cohort is expected to have demonstrated, prior to entering graduate school, the skills and accomplishments meriting admission to an advanced degree. As I mentioned above that was not in my view the case in US Universities, wherein the bias was to accommodate later specialization. Which means that more generalists entered graduate school in a demanding discipline, which leads to the advanced courses and so forth.
Another more subtle cultural bias seen at the graduate school level is the "dog eat dog" approach. I cannot say this does not exist in Europe, for that would be blatantly untrue. But, here it does seem more prevalent. This is seen in the following fashion - that there is an expectation for the research to yield results. This is not unreasonable if the research topic is sound and fecund, but, sometimes the advisor (Professor) and researcher (student) may simply miss the mark. What really matters then is the reaction to the problem of finding oneself on stony ground. In this regard the Professor bears a significant responsibility as they are the wise counsel to the student. At it's worst a Professor may simply demand more application of effort, which sounds like what may have been happening with you, in place of actual thought and imagination. Bottom line, too often, in the grasp of a poor faculty member, I have seen graduate students flail about trying to find a positive escape route from graduate school. Working 80 or 100 hours per week will not help if the furrow you are ploughing is barren. In truth, I doubt that forcing a graduate student to work such long hours is any guarantee of success. In my experience such long hours are best spent when the field of research pursued is fertile, and the researcher self-motivated by small victories, or giant leaps forward.
Working 80-100 hours per week over a doctor's objection is simply foolish. They should have given you an opportunity to take a respite, returning at the next quarter or semester as appropriate. Not receiving appropriate, unbiased support from an ombudsman is simply appalling.
I can speak to this last part having recently had a family member undergo something parallel to your experience, though at the very earliest stages of their graduate school experience. For medical reasons the doctor's advice was to take a sabbatical, or at least cut back to a normal work load. As the latter would not fit the needs of even a lenient graduate school requirement they elected the sabbatical route and all funding will remain in place for this person's return. The individual in question was also ill-equipped for some of the high level courses the advisor insisted be taken - above and beyond those really required - purely to fill out a Professor's class size. My advice on the issue was to find a different advisor on returning, but that is a different story.
All in all, the experience you hint at, and those I have seen suffered through by others points to one conclusion. The most critical choice an entering graduate student can make is the choice of advisor. They should be more than co-author on your papers. They should be your champion, not your task master. Your guide, not your grinder. As buckiprof notes, he was already familiar with the Professors with whom he worked in graduate school, having seen them over several years as an undergraduate. Of course, in the US that is atypical. Often a graduate student will make application elsewhere, and thus have little prior exposure to their future advisor - except on what amounts to a recruiting visit. A different model applies overseas, more in line with buckiprof's experience, moving to a different school is not unknown, but it is not the norm. The likelihood of a mismatch somewhat diminishes.
Sorry if this was long, but the deficiencies of this part of the US educational system happens to be a subject about which I also have strong feelings.
