High on the list of things I never thought I would do a second time: Write a dissertation proposal. Not that the original experience was anywhere near as scarring as, say, my comprehensive exam, but neither was it a joyous experience I yearned to repeat.
But, Experiment 4 of my dissertation is killing me. For assorted technological and practical issues, I have given up hope on it working - and did so just as reviews came back declaring Experiment 4 to be absolutely vital for our interpretation of other dissertation findings. My advisor didn't want to let the experiment go. I told her that the experiment was toxic, and that I would sooner pursue an alternate career than get it to work. I was only slightly exaggerating when I said I was starting to think longingly of a career at McDonald's.
Our compromise: She will back me on changing the experiment, if I can restructure the dissertation so the research seems motivated but the current Experiment 4 doesn't seem so obviously necessary. I am to write her a dissertation proposal, which she will approve (or not), and which I can then send to the rest of my committee so they at least have a "heads up!" that the dissertation has changed before I plop it into their inboxes.
It is a good compromise, and it's not like I had much else I would have been doing for the next few weeks anyway. (The original plan was to write later chapters of the dissertation, but the motivation was no longer there). If I get frustrated, I can console myself with the knowledge that at least this time I only have to convince one person, not five.