When it comes to designing and building websites, it never seems to happen fast enough.
Given this fast pace, many small details that are eventually required to build the website are often left out of the design process. While these details might be minor, they are what take a website from nice to truly awesome.
These details are often easy to miss because they don’t drive the overall look and feel of the website. The problem is that as your development team works through the design, it will be forced to design and create these elements for you anyway.
You could adjust the production cycle so that the developers have time to return these assets to you, but why not just get it all done up front so that the process is that much cleaner?