Is it wise to write a book with a target audience in mind?

No. This is only my own personal opinion but I don’t believe you should write a book with the intention to hit the big time. You will do yourself a disservice by writing something that doesn’t come from within, or in other words – you’ll be called a sell-out. You should always concentrate on writing the story you want to write and stick to your guns. If you finish writing your novel, and you are 100% happy with it, then that’s all that counts. If you are receiving rejection letters from agents and publishers with your gold bar of a book then don’t be too disheartened. J.K. Rowling and several other authors got rejected too, and if you get to the end of your tether with agents and publishers, then at least there is always the self-publishing option. If you try to write the next Harry Potter, or the next Gone Girl, then you’ll most likely run into problems in quite a few areas. Use your influences wisely – don’t copy them! I also don’t like the word “brand” when authors, or anyone else involved in artistic virtues, describe their works as a type of brand. It makes it sound as if I have created something that washes underpants like washing detergent or soap. Brand makes it sound as if the story or book you have just written will be the forerunner to anything else you may write in the future, and this, in my opinion, will pigeon-hole and typecast you as “that author who writes horror” and only horror. Stephen King has said in his book On Writing that he never defined himself as a horror writer or any type of writer specific to a genre – other people did that. Having said that, it could be said that you will write in a certain style and this is fine, but some of the best authors surprise us and keep surprising us by being different.