Clients sometimes ask us what the biggest challenge is in creating a website, app, book, or whatever. There's no end to the number of things that can be potentially troublesome in any project, but the answer that always comes to mind first is “content.”
It is, I admit, in a close race with color (color generates emotion, in lots of ways), but content is the top banana peel. And that makes sense. It’s the whole point of the project—any project.
When content is the problem it’s usually not because nobody thought of it or planned for it. It’s because it looks and acts differently when it’s in place. A text document or Photoshop image reads completely differently when it’s combined with all of the other stuff on the website or in the book. The size, shape, flow, and overall impression creates an entirely different effect. And sometimes it’s just too long or too short.
There is no way to stop that from happening. But there is a way to stop it from being a disaster: allow time to review the content in situ, and give the content owners the tools to adjust as they see fit. As the project is moving into content integration, plan a phased progression so that everyone who needs to can see the results as they happen, and the people who write the text or make the images can jump in and change or refine as needed. Content management systems have finally arrived at the point of making this possible for web work, and wiki-like PDF features have made it possible for print.
It’s not a massive change of procedure, it’s really just formalizing and providing structure to a process that happens (usually in a panic) anyway; so it smoothes out the process.