And so on and so forth, ad infinitum.
Indeed, we commonly judge works by the kinds of compromises writers tend to make. An author who chooses style and ideas (especially the style and ideas fashionable at the moment) over accessibility and entertainment value is dubbed "literary"; one who chooses the opposite is likely to be labeled, or dismissed, as a mere "genre" writer.
All of this reflects the reality that even the most able and versatile author will generally not be able to do everything at once, not in a single passage, not at the level of a whole book. Some imperative will go unfulfilled, some standard unmet, some taste unsatisfied.
It should be remembered, too, that few writers can do everything that we look to writers to do well, even if given the chance, because every talent has its limitations, if not of ability, then at least of interest. Some authors excel at action, but are incapable of writing dialogue that does not hurt the ear. Others write beautiful prose, but cannot plot to save their lives.
Then there is the Sisyphean nature of the editorial process. Any one adjustment in a manuscript (eliminating a minor character, shifting a scene earlier or later in the story, etc.), especially the kind of tightly written manuscript to which we are supposed to aspire, calls forth related adjustments throughout the same text--making for layer after layer after layer of edits. Then it all has to be proofread, a process which will likely lead to still more edits.
And of course, one can always go back for one more round of polishing, making the process potentially endless. If everyone did that, of course, nothing would ever get finished, and there are plenty of reasons why writers do not do so, besides deadlines and the limits of human endurance. Just as in any other activity, patterns of diminishing returns can set in here. Even negative returns are a danger--the process, past a certain point not merely a waste of time, but likely to leave the book worse off as an obsessive writer goes back and undoes what may not have been perfect, but was nonetheless worthwhile.
And no one knows this better than the writer themselves, having pored over their books so much longer and so much more intensely than anyone else ever will, more conscious of the compromises and the editorial scar tissue than any mere reader is ever likely to be--and if they have any self-respect as an artist, harsher on themselves than any (fair-minded) critic.
The result is a love-hate relationship between authors and their work, memorably described by Winston Churchill. A book, he wrote, is at first
a toy and an amusement; then it becomes a mistress, and then it becomes a master, and then a tyrant. The last phase is that just as you are about to be reconciled to your servitude, you kill the monster, and fling him out to the public.Alas, very few writers are actually in a position to get that kind of closure. Mostly they just collect form rejection letters, after which the would-be books continue to lurk in the drawers of their desks and files in their computers like the monsters in a child's closet, awaiting their chance to tyrannize again.