At the start of a project there are many different objectives and everyone involved has their own sense of priorities or tasks they wish to a tackle first. For me that is generally sorting the backend into a nicely organised structure that will allow flexibility in the output both now and in the future.
A big part of this is getting real data in so the front end output is as close to final content as possible. This allows us to realistically analysis how the content and design will work together.
Does it Fit
As flexible as the web is with it’s layouts there are still times when a design will only allow a certain amount of text or number of items to appear before it looks squeezed. For example text in a sidebar can be excellent if it’s short and snappy. However if the actual content is a long paragraph it will be very hard to read.
I’ve also experienced this with titles where they can be in a large font size. Taking into consideration how that works over multiple lines is a useful exercise.
Adding columns or boxes to a layout is a useful way of defining content areas. Without real data these areas normally contain filler text, occasionally the same filler text, which can mean boxes are the same height as each other.
On many occasions I’ve seen a design change as soon as real content is output as one boxes contains many more lines than the other causing them to no longer vertical match in height.
This is normally the realm of imagery as it is the hardest part of content to populate. Instead of just using test images take the time to ensure the design works with other no images or a placeholder repeated multiple times.
Content editors often need to add some classes or styles to text entered in wysiwyg editors to help front end presentation. By their nature these editors don’t or can’t always output perfect markup. By using them to populate the site at design and development time you can save a lot of headaches by utilising the markup they do produce and not battling against it.
On every project I find the use of real data and content smooths out the development process as all involved parties can see a “real world” example of how the site will function with it’s content.