I use often Google to find a certain theme on my own sites.
The customized search is set to all my domains, Wikipedia and other for me important domains.
It often happened in the last month, that I did not find the pages, I searched for.
Now I made at several domains
and clicked through the list until the end was reached.
But the end was reaches far before. The most extreeme case was
1060 : 416
This are all pages with original written content, an other case was
948 : 591
I searched my old referer log statistics for certain pages not listed.
They received in the past traffic from Google with unique search terms not available on other pages from me. So this are not "never found - so unimportant pages", they have been found earlier for unique content.
Has Google Alzheimer?
I write here about domains having 5000 to 30000 visitors per month by Google and PR3 to PR5 on the start page.