Permanent redirects, also known as 301 redirects, are the life blood for webmasters when they make changes to their URL structures. It is common practice and knowledge, that when you change a URL from one location to a new location, you want to 301 redirect that URL to the new location. This tells Google and other search engines that the URL is no longer at location X but has permanently been moved to a new location.
Sometimes, Webmasters have to set up a double redirect (or sometimes even more) for one reason or an other. For example, abc.com/page1.html has moved to abc.com/page2.html and the webmaster set up a 301 redirect from page1.html to page2.html. Then, abc.com/page2.html had to be moved again, this time to abc.com/page3.html. So the webmaster set up a redirect from page2.html to page 3.html. If a search engine or user went to page1.html, they would be redirected to page2.html and then redirected to page3.html.
A Google Groups thread asks if Google can support this "double redirect." Googler, Berghausen answered that Google can. He added that the "process might take just a little longer for double-redirected URLs than it would for single-redirected URLs." How much longer exactly? That is unknown and depends on many factors. If it was a single double redirect, I assume it would get picked up quicker than if it was hundreds of double redirects.
Overall, it would be best to bypass the original redirect to make a single redirect. So in our example above, redirecting page1.html directly to page3.html would be the mode of action, and making sure to set up the page2.html redirect to page3.html would be necessary as well.
Forum discussion at Google Groups.
