For a photo book created with BookWright, you must have a minimum of 20 pages.  If you are using less than 20, you just can't delete the blanks.  You're not paying extra for those blank pages, because the starting price for a book is for 20 pages whether or not you use them.  The important question is whether the number of pages you use is the right amount for the purpose of this book.  I wouldn't try to fill up the blank pages with unnecessary stuff just to avoid blank pages, but they are there if you need them.