Ok, that might seem obvious or even silly, so lets look at another example. What about if you had an online store which sold American Football Merchandise, but specifically for the Miami Dolphins. Or baseball caps, but only for the Boston Red Sox.

If you looked in Google, you would see that a term like "baseball caps" or "football shirts" would get thousands and thousands of searches a month. However, even if you managed to get 20,000 of those to your site, I can guarantee that only a fraction of those would buy your products.

And now you can probably see that the reason is obvious. The few you get would be those that by CHANCE are Miami Dolphin fans. Now, merchandise in its own right is broad, so if your site sold different item of merchandise, then you might want to split these into separate pages.

So, if you had a site which sold merchandise for various teams, then you would have a separate page for each team, and make sure that the keyword that takes them there relates to exactly what they see when they land on it.