So far and from my understanding no minimal and maximal post required to earn merits and if you post something that is helpful to community you would see merits coming like flood to your profile,as a matter of fact a single post can possibly earn you up to 100 merits depending on creativity and useful you information could be. The thing is most of the topic created by newbie are the topics already created but just that they always reform it make it looks like another post or I will say there is always a particular methods mostly used by some newbie to earn merits and since lots of people knows giving out merits to similar post could be very hard.
Yes, there’s no minimum or maximum post needed in the forum in order to earn merits. Earning merits does not matter on the quantity of the post, but rather on the quality itself. If you are only able to make a single post and yet that post becomes very relevant and useful for majority of the members, in no time you will receive series of merits. That looks very easy to achieve but actually when you are not a good and quality poster, you will find it the hardest.