Some threads were started months or years ago and have got zillions of replies so its impossible to read them all.
A good idea is to click on 'New Posts' at the top of the page every time you come into A2K, and choose which ones you want to answer.
If you want to narrow things down even more, click on 'My Posts' and a list of threads will come up which you've posted in, and you can go in to check how the discussion is progressing..