How updated is "The Linux Documentation Project"?

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http://unix.stackexchange.com – I have been advised by many senior Unix/Linux Administrators to go through "The Linux Documentation Project" on the site www.tldp.org. Its undoubtedly a very rich site, but I saw many tutorials (as seen here and here) to be more than 3 to 5 years old. I do know and understand that it is definitely worth to go through them thoroughly at least once, but I just want to know that if for topics which are important for me as a learning linux administrator, should I also search for latest articles on same topic on internet? Hope I do not offend any one with this question. (HowTos)