tedster - 6:45 pm on Jan 13, 2008 (gmt 0)

There's no hard and fast rule about how much new content is "too much". If you're adding real content of the written article variety (rather than outputting new urls generated by searching, slicing and dicing a database) then it's almost impossible to get into trouble. You can add thousands of urls at one time without tripping a problem, and you probably cannot write that fast.

In terms of when content is considered stale, that too does not have a rigid definition. Google patents indicate looking at backlink growth and stagnation, for instance, rather than just looking at a published or last-modified date.

Some types of content (say, product help files) are expected not to change very often, whereas other types (like a news site home page) are expected to change frequently. So I just do what's right for the website's users and let Google sort it out however they want.