Please, by all means, post in older threads if you have something useful to add.
Equally, if all you want to say is ‘cool, thanks’, then if the person has survived for a month without your thanks, he’ll probably live on without it. If you really want to express gratitude, pm the author. It’s quite frustrating to go into ten different threads with new posts only to find that each of them has been resurrected to say ‘cool, thanks’ or similar.
PS - I’m not trying to offend or pick on anyone, just had to get that off my chest.