Sometimes you may have a page address that might change. For example, if you had a special offer each month you might have pages called January.html, February.html, etc. Rather than rely on visitors entering the correct web address you could have a redirect page called this-months-offers.html, which would automatically transfer them to the appropriate months special offers. All you would need to do is to remember to change the Redirect URL for that redirect page each month.
Another time where you might want to change the address of a page on a regular basis is if you are making recommendations and those recommendations change on a regular basis.
For example, you might have a link on several pages on your site that says Click here to get the best quote on insurance. Many people would make the mistake of having this link point to a specific insurance company, but if you use a redirect page you can point the link to the redirect page and then change the insurance company you are recommending whenever you like just by editing the settings of the redirect page. This saves you having to go through editing the links on all the pages of your Web site.