Timing Rules
One of the major reasons for writers to observe the timing rules (discussed
above) is to ensure that they achieve the maximum quality for their effort, by
allowing for proper regeneration in the lay off period, sufficient review and
careful editing. While this does not answer the question directly, it indicates the
folly of not following the timing rules because if you do not, you are always
needlessly writing below the level of quality that you can achieve.
Opportunity to Rewrite
Another relevant consideration is whether you will have an opportunity to
redraft and republish the writing. This is one of the great strengths of a
textbook because generally textbooks are rewritten periodically to bring out
another edition. While the immediate compulsion to write a later edition is to
bring the material up to date, a second function of the latest edition is to
rewrite and rearrange the text to improve it. The point to all this is that if there
is to be a subsequent edition it is often efficient to do a reasonable version first
time around then to use the second edition to do more intensive polishing,
editing and reworking. By then you have had a break from the book, with time
to regather your own ideas and to take on board comments from readers,
colleagues and reviewers.
Time Constraints
A time constraint will always answer the question of when to cease writing.
Once a manuscript is due in to a publisher all writing must cease. If a judgment
has to be delivered by a certain date it has to be delivered.
Experience
There is no substitute for experience. Experience gives self knowledge, which
enables you to judge better the level of quality that you need to have for any
particular piece.
Style Manual
A good style manual for Australia has been produced by the Commonwealth
Government Style Manual (2002) 6th ed John Wylie: Australia.