Why MS Word, you ask?
I am ordinarily an avowed plaintext person, and I have tried everything from various wiki formats, org-mode, markdown of every shape and stripe (even bought a few markdown editors), but they haven't worked for me. The reason is lack of WYSIWIG
WYSIWIG is a huge efficiency booster. Inline images, doodles of my own, colors, fonts, tables, inline math, greek and other symbols, all of it is right there in the original (not in a separate render), and is searchable.
Having all of it in one file is not really a problem performance-wise; I have had one file for the last 8 years. It is easy to back up and the chronology is clear, and it is easy to generate a table of contents.
Finally, having it on a google drive means that it is available/convertible to google doc if I need to access it from elsewhere. I do not rely on google docs to be the primary copy, because i don't want to rely on a working internet connection all the time. Offline works better for me.