I noticed in Webmaster Tools that pages on my site that were renamed or deleted many years ago are still coming up listed as not found even though there have never been any links to these pages.
So is it necessary every time you change the name of a page, to keep the old page as a 301 redirect to the new page? Or will Google just figure it out over time?
My site has gone from two websites:
www.example.com and a mobile version
m.example.com, now merged into just one
example.com that works in mobile and desktop.