The bad news about time management in the academic setting is that it is very fragmented, broken up by interruptions of classes and meetings, emails and grading. Many people don't have four or five straight hours each day in which there is nothing else scheduled.
The good news is that you only need 1-3 hours a day for your writing. You can schedule writing the same way as anything else. Instead of seeing time as fragmented, broken up into unusable shards, take control yourself and break it into usable segments. One of the worst excuses is that "I only have 15 minutes, so I can't get any writing done." 15 minutes is long enough to run a spell check, to look over a few sentences, and to maintain continuity on a project.
I am proctoring the PhD exam tomorrow. That will let me get three hours of my own writing done.