Sure, the quality of your post will determine if you're going to earn Merit or not. You can't be making posts that only covers two or one and half line and start hoping that some day you will get merited no, it never works like that. and sometimes making a lengthy post will not guarantee or qualifies you to earn Merit, Because I have seen several posts that is very lengthy but not meaningful this way you won't be eligible to earn Merit.

Yeah, making a post in a quiet threads seems like a waste of time. As you will not be recognized, so post need to be make in those threads that is always active 24/7, This way you can easily be recognize by those high rank members.