This is an article I wrote back in the earlier part of last year (2015). It will perhaps be of use to students and academic writers.
A principle which appears to me to be a good one, which occurred to me some time last year, concerning writing, has been:
When preparing to write, start from the broadest context that the purpose of the document can possibly allow;
Then identify the broadest possible sub-divisions of this context;
Then give the broadest possible descriptions of these sub-divisions (though these descriptions should be broad, they must still be accurate);
The further each sub-division is pursued, the more evident will become the things that are less relevant to your chosen sub-division, and, so, less likely to receive much attention in the document itself, if any at all – (though it may well be beneficial to include some measure of this information in footnotes or appendices, for the sake of clarifying the research context, for both the comfort and benefit of the reader);
The sub-division which is the topic of the dissertation should also be attended to, and the writing on it completed, in the way just outlined above: with appropriate contextual information, subdivisions of the topic, etc.
Matters that are of broad relevance to the main topic of discussion may need to be mentioned no more than once;
The more relevant a broad matter is to the main topic of the discussion, the more will need to be said of it; the less, the less;
A matter that is of the least possible relevance to the topic, whilst still having some meaningful bearing on it, may receive sufficient attention by being mentioned only in passing.
The more relevant anything is to the main topic under discussion, the more it will need to be spoken of; but we must say nothing but what is relevant to the subject – no less or more.