I suspect you're right in that it's never given you all the results. I'm pretty sure that it's given me many more than 300 or so results in the past, though, whereas that figure seems to be google's idea of the max any user could possibly want now before they refine their term.

I think mars is probably not the ideal term for testing this sort of thing - just too many hits. I tried mars "philip k dick" and found the same thing - 30 or so pages and then it refused to give me more results. Increasing the obscurity level somewhat, devil's vindata vanilla search vs. verbatim search did indeed show a reduced set of results for verbatim (the vanilla search results including hits on devil's vendetta)

Overall though, if you're looking for more fringe results for common search terms, millionshort.com might be worth a try, where you can remove hits from the top 10^n sites for your term it says.

It used to give you 1000 results (100 pages). Then it changed because 'nobody' goes to those last pages and it's very expensive to keep those big sets. Then it dropped to 300 or so. Then it became 'some random number between 20 and 300 depending on invisible factors'. Pretty rare to see a resultset with more than 200 pages. Even 'webcams' (of which there are 10's of millions of pages) gives only 323 results.