To what degree does the content of a fiction writer's literature reflect their innermost personal dessires?

I think you paint with too broad a brush in your details. I have some friends that write fiction, and how their desires are reflected are much more subtle. One friend often has dogs that her protagonists rescue, she has always loved and wanted dogs, but her husband doesn’t like or allow them in the home. Another one used to be a cop, is now a PI, and writes cozy mysteries that are not procedurals, he just understands the formula involved and does it well, so makes a decent retirement income from it. Women who write “romances” often can’t get published unless they target their work for the genre publishers.

Basically I think (and the work of my friends reflects this) that aspects of their lives are used in their work, attitudes, descriptions of places and people, etc, but not so much the grand, broad, themes that you suggested.

I do not think it is too farfetched to think that, if a specific type of content is virtually all they ever do. Someone needs to investigate Scorsese. All he ever does is mob movies.

“Does what an author writes reflect their personal preferences or desires?”
– Sometimes. Not always. It varies.

Not usually. Think about what you are saying. A murder mystery could be a deep seated desire to kill someone OR it could be a fascination with solving mysteries to put bad guys behind bars. In every story you mentioned there are two sides at least. So if the author is describing a murder, he might also be catching and punishing the killer. If he is writing an action novel, he might be showing fighting, but it might also be defense or again, catching bad guys. A romance novel might show a hero/heroine that is lonely but also shows the person that is solving that loneliness.

Many novelists’ first novels are semi-autobiographical but after that, most good ones develop other plots and characters. I’ve heard writers talk about their inspirations and many say they draw from various people they know and plots they hear but also totally fabricate. And genre writers may just pick a winning formula and stick to it. So I don’t agree with the statement at all.

In as much as it is true it isn’t so much a reflection as a transmutation that can make gold out of lead.

There is a manga/anime called “Redo of a healer”, where the main character is a serial rapist, whose justification for his crimes is that the women he tortures and rapes did the same to him in a prior time loop. Of course, that is not true of all of his victims, as if that even was a justification. Some of his victims he picks up along the way and he gaslights/brainwashes them into being his sex slaves.

The author’s follow-up work is a story about an assassin who gets reborn in a fantasy world.
His first female companion is an orphan that he brainwashes.

It is difficult not to conclude that the author is heavily afflicted by deep-seated misogyny.

I’m not a novelist, but I do tend to tell stories when I write songs. I’m sure there are as many answers to this question as there are novels, ranging from the “definitely yes” category, as expressed by @ragingloli, to the “definitely no”. Kurt Vonnegut, for example, has novels that seem to be partially autobiographical, to some that seem in no way related to his life; yet all of his novels, indeed all novels, novellas, short stories, manga, songs, paintings, sculptures, yea, all works of art reflect the artist(s) own experience in some way.

I have several songs that are directly autobiographical, and relate to some specific event in my life. Others are pure fiction, but they are based upon real feelings from real experiences.