- Be more discursive. Interestingly, Merriam-Webster defines discursive as either (1) rambling or (2) proceeding coherently from topic to topic, an interesting case of a word in English also meaning its exact opposite. But I'm being discursive (in the first sense). I often find that students are too terse in writing their theses. I think this stems from the fact that they've been buried in a problem for months (or even years in the case of a Ph.D.) — many aspects of the problem are "obvious". But this isn't the case for the reader, who may be encountering the problem for the first time. In my experience, this happens most frequently in the introduction, when explaining the setup of the problem, what the research is trying to accomplish, etc. Remember, theses don't have page limits! Walk the reader through your arguments; explicitly spell things out.
As a general rule, I will do a detailed read of your thesis once. By detailed read, I mean with a (virtual) pen in hand, marking up your draft. You tell me when you want me to perform this pass: I can do chapter by chapter, entire thesis at once, or something in between (allowing for a reasonable turnaround time, of course). The factors to consider are that if you ask too early, the draft might still be very rough — with issues that you could have caught yourself — thus making it a poor use of my time. If you ask too late, you draft might be too set to make major changes based on my feedback.
I am, however, happy to skim parts fo your thesis multiple times if you just want a quick sanity check. By skim, I mean I'll flip through the pages, look at the figures, read the section headers, etc. Don't expect me to catch typos.
The only exception to my rule is for the abstract and certain parts of the introduction (e.g., contribution statement). I will go over, in detail, those parts multiple times with you to get it right.