I'm going to throw a wild number into the mix, to show that what Donna says ("it depends") is absolutely right.
A few years back I contracted to do a content survey of an intranet in 2 weeks. I thought it was a crazy short time, yet there was a lot of merit in just setting a time limit and then stopping. It's hard the first few times to estimate job time. When the client gives you a time limit, you figure what you want to achieve in that time. I think usually it's better to do a light survey of the whole than a thorough survey of a fraction of the site.
The report was simply 17 pages of spreadsheet, plus a brief summary.
Setting up the spreadsheet was crucial. Turned out the intranet had about 30,000 pages of which around 20,000 were obvious ROT. The survey was more than adequate for the client's purpose. It was obvious the intranet needed more than just a tidy-up.
I certainly didn't view every page where I found lumps of similar content. Instead I had a column labelled "links to". For example, one page linked to 18,000 pages of 'old what's new': I skimmed a handful to make sure they were all a similar type of content before moving on.
For this particular survey my columns were as follows, because this was the information needed by the client.
1. page numbers in my own system (e.g. 2.1.3, or if the row summarises a section with 65 similar pages, 2.1.3.1-65)
2. page name
3. content type
4. date
5. ROT — the most important column!
6. notes
7. URL
8. Links to
9. owner
Hope that helps.
Rachel
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Rachel McAlpine
Contented.com
PO Box 19244
Wellington 6149