I have been climbing more than usual lately (twice a week hard)and while I do not have any hand injuries, my hands (ligaments I guess) do feel really tired. Almost strained. I figure I need some time off but was wondering how long I should take before I ease back in. I don't want any injuries.
Age is pretty relevant. This is a tired (hehe) subject. Check out the book "One Move Too Many". pretty comprehensive coverage of climbing injuries (most of which are hand related).
Short answer - if you are old(er), it takes more time. If you haven't been climbing for very long (weaker ligaments, pulleys), it takes more time. If you are climbing too much, it takes more time.
Also, there is a fine line (and important line) between soreness and pain. I find that soreness is good. It means you are pushing yourself and your body to the correct level. Pain (pulleys, joints) is a bad thing and means you MUST take at least 1 month off. Otherwise you are just chasing an impossible goal of achievement/injury.