When writing an ad or a brochure (or even a blog post), repetition generally isn’t very helpful. You have a limited amount of time with your reader, and you need to make every word count. Besides, if you mention something once, you usually don’t need to do it again.
I’ve seen people try to apply that same logic to copy for websites. They’ll ask me delete an item or section on one page, noting that another page carries the same information.
But repetition isn’t a bad thing when it comes to websites. The key thing to remember is that people don’t read them the same way that they read brochures and other forms of printed communications. While most people will go through a brochure in a linear, start-to-finish process, they go through websites with specific goals in mind. They’ll drill right down to the information they’re after without even a glance at the rest of your site. They may read only one page in twenty – but what’s on that page is what’s important to them.
The lesson you should take away is that it doesn’t hurt to have some repetition on your website, particularly if you’re trying to convey something that’s very important or a key differentiator. Don’t assume that every visitor will pursue every page of the site. Instead, develop copy as though they’ll only look at one page. (That kind of thinking will benefit your SEO efforts, too.)