Some sales people can genuinely think on their feet, and work better that way (many more do it just because they’re too lazy to work out the sales story for each prospect in advance). But they’ll probably agree that a few minutes’ planning session before an important sales call is worth the effort. Buyers expect a coherent pitch which is tailored to their circumstances.
The same should apply to your content creation. Really, when you’re putting together a web page, you’re just putting together a written sales pitch …even if it’s a product description. So don’t just sit down, write the headline, and then list one fact after another until you feel there’s enough there. Your best sales people won’t do that: after establishing what the buyer wants, they’ll show how the product can meet that need and discuss its benefits, then go through the features which provide those benefits. Finally, they’ll “close the sale”, which in your case, might be simply getting the prospect to make an enquiry or download a brochure.
If you’re going to spend an hour creating a web page (or any sales document), it makes sense to spend five minutes sketching out the structure of the argument first. Over the next few years, a lot of important people are going to see what you’ve written. Tell a good story, with a beginning, middle and end.