Should I be using rel canonical here?

[MarieHaynes]

I am reorganizing the data on my informational site in a drilldown menu.

So, here's an example.  One the home page are several different items.  Let's say you clicked on "Back Problems".  Then, you would get a menu that says: Disc problems, Pain relief, paralysis issues, see all back articles.

Each of those pages will have a list of articles that suit.  Some articles will appear on more than one page.

Should I be worried about these pages being partially duplicates of each other?  Should I use rel-canonical to make the root page for each section the one that is indexed.  I'm thinking no, because I think it would be good to have all of these pages indexed.  But then, that's why I'm asking!

[AdoptionHelp]

I've begun using this tool to compare pages for duplication. On the page they say 80%+ is duplicate, but I would be far more conservative.

http://www.wordsfinder.com/tool_duplicate_content_checker.php

[EGOL]

I would not worry about this if the level of duplication is a small percentage.

However, if you have pages that will share a large percentage of the same items then it could be a problem.

The question is:  How much is a "small percentage" and how much is a "large percentage".  Duh?

I know of two blogs that have every post going into between two and six categories.  This produces category pages where every post appears somewhere else on the blog in multiple locations.  However, the lists on these pages are diverse.  None of the categories are mirror images of one another or even share 25% of the same posts.  These blogs have not experienced any problems.

If you think that you have too much duplication then you probably have too many categories.  Or, you are too liberal in assigning items to multiple categories.

[gt3]

I would try to add some unique content to each page. So, if you have a page about Pain Relef, try adding a paragraph on top about it. I wouldn't worry about duplicate links unless the whole page have exact duplicates.