This post on Quora by Chris Wake provides some food for thought. I think Chris’s list of “habits” isn’t completely accurate, but they certainly serve as red flags to help assess if you’re not quite as productive as you think you are.
For example: the habit “consuming more than you create” is not a cut-and-dry issue. I, for one, read far more than I write. But that is needed because a lot of what I write is based upon the things I read. For me, “consuming” is a huge part of the creation process. But there is a difference between things like researching, drawing inspiration, and learning, as opposed to lurking, procrastinating, and vegging out. The former is effective, the latter is not.