Robert_Charlton - 7:08 am on Jul 18, 2013 (gmt 0)
For a given definition of "made sense", at least. "I don't like it, I don't understand it, but I accept it as fact."
lucy24 - And here I thought you'd come around after your first post above. ;)
I highly recommend that thread to anyone with lingering questions about the Google crawling or indexing process.
It takes a long time for google to process noindex.
dethfire - How often does Googlebot visit the pages you noindexed? That would affect implementation speed.
Also, regarding how fast noindex is implemented, getcooking makes a very interesting comment on this crawl allocation discussion about Google's crawling behavior on noindexed pages (more particularly about removing noindex rather than first implementing it, but there might be related behavior at the head end)...
Crawl allocation and duplicate content
I track all googlebot activity on my site. On my noindexed pages, google slows down the crawls over time. So, once it picks up the noindex tag and removes the page from the index it starts to spider that page less and less frequently (once a day, then once a week, then once a month, etc). It will still eat some of the crawl budget but Google seems to be good at reducing how much effort it puts into those pages. It's probably also why once you noindex a page it can be a long time before you can get it reindexed. That's been my experience anyway.