Is there such a thing as too much work for a Master's Thesis? My thesis  (Canadian Research Based, Computer Science), collects three separate research projects (with a tenuous connecting thread). 

While collating these projects into a single document, I have looked into other theses coming out of my university and others in my field, and have realized that it's looking like my thesis is going to be very large. Probably twice the average length of others in my field. 

Which makes me wonder: Did I do too much work for a thesis? Should I have pushed my supervisor, cancelled the final proposed project (#3) and graduated on the strength of the first two? 

I'll be graduating 6 months after my target deadline, with multiple publications, and so burnt out that my initial plan to pursue a PhD has collapsed. Can't change the past, so I'm asking here mostly out of curiosity, and for other future students.
It is not clear how to judge the "size" of a thesis (page length or word count is probably not very good), but one can clearly do too much research for a Masters or Doctorate. That said a factor of two difference is not really that big since there is always going to be a healthy overlap between the "largest" Master thesis and the "smallest" PhD thesis. If your Masters thesis is larger than the average PhD thesis and larger than the vast majority of Masters theses, then it is possibly too large.

As a student you need to be asking yourself why you are getting the qualification. Most students put in much more work than that which is required to simply graduate. You should make sure you push your supervisor to help you achieve your goals.