Each post is perceived differently by different people. Post can be useful for one person and useless for another. So when You write a post no need to think about Merit.
You should try to convey to people what you want to say in simple language. This is My opinion.
Exactly.
At first you write a post in order to share with people your knowledge or any observations or just interesting information and then if they find this post useful you will be merited.
Its not worth writing a post just to try to get merit, it's not work like that.