Well, I don't review every book I read. I do read quite a few romance novels but I just don't have much to say about them. I would rather give my point of view on historical fiction, action/adventure or mystery/suspense, which I read a lot of. I have been trying to get into the habit of reviewing most of these type of books as I think it might help my chances on getting more ARCs, plus I like to go back and see what I wrote as a comparison for other books by the author, or similar authors. I write my review immediately after I finish the book or within a couple days, otherwise I feel I can't move on to another book.
Ever since I started blogging I have reviewed a majority of the books I have read. I definitely review the ARCs I receive from LibraryThing's EarlyReviewers program and other programs. There is only one book I received from the ER program that I have not yet reviewed. I always post my review to my blog, LibraryThing, GoodReads and Chapters Community.