It's hard to know whether you are going to be a book person or an article person. At one point I decided not to worry about writing any more books, but a few years after that I published two books. Now I think I'm book guy again, but in the meantime I'm doing a lot of articles because of all the invitations I'm getting.
The problem with the academic system as it's set up is that you need books for promotion, but articles on a year-to-year basis. Writing articles can be a distraction if what you really care about is the book. A book should be at least 50% unpublished in article form, so you have to worry about not publishing too much of it. On the other hand, if that book never gets written, you want to have something to show for all that work.