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Have you though about your 'extra' or 'outdated' content being 'noindexed'... It can still be accessed by visitors and SEs. It's still a resource for visitors. It can still 'pass link juice'. It will no longer 'clutter up' the results.
Maybe, set a type of a 'date' indexing procedure where content over N days old is removed from the index ('noindexed'), or maybe base it on topicality and when N new pages appear on the same topic the older pages are 'noindexed'?
Again, Use at Your Own Risk... If you remove your old pages from the index and they're the ones driving traffic, you will lose that traffic when you remove them and if your newer pages don't rank you just dumped all your traffic.
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