Your mileage may vary, but I can't conceive of creating anything written or graphical without knowing the context in which it will ultimately be applied.
For those of you early PC users, you might recall the blank screen of WordPerfect 4.2 taunting you with a lonely blinking cursor waiting, no...daring, you to start drafting your creative work.
Well, creativity may fundamentally begin that way, but it is stimulated by at least visualizing if not actually seeing the context in which it will breathe its life. Is what you write unaffected by where it appears and how it is ultimately used? Of course not. Even if the message is essentially unchanged, I can't conceive of using the same words, length and style for a:
Consider what happens if you try to communicate the message via some form of poetry or, dare you be so ambitious, a haiku?
The same is true when the medium
The message is packaged differently for a radio spot than it would be for a corporate-image print piece, and more so yet for a Web presence. Fortunately, today's tools of technology encourage, in my estimation, performing the development work in a presentation-design mode.
I call it Create-In-Context. In fact, a telling example is how I too often use Macromedia's DreamWeaver. Although I admit to often using this compelling application to quickly add Cascading Style Sheet (CSS) styles to text, doing so generally happens in the context of authoring the living text for the body content. Yes, in many ways, DreamWeaver's most compelling asset for me is that it allows me the luxury of creating in context that is, I am able to write by page text in the framework of the design in which it will ultimately appear. And I mean this in more than an "all the news that fits" perspective. I also use this environment to gauge the appearance (visual design and greyness) of a page with the words in place, as well as to see how the content works with the design in general and any inline or wrap-around images as well.
But I digress, which is not uncommon, I suppose.