In my opinion, merit should be given based on the quality of a post and how useful and relevant that post is.
- If the post is good and the topic is old and known to everyone then it should be awarded 1-2 merits.
- If the post is new and useful then it should be given 2-3 merits.
- If the post is too good and benefits more users, then it should be given 5 merits and more.
But the assessment on helpfulness is very subjective. Different users have different assessments on one helpful posts which result in different sendable merits will be sent to that post. The first point is not too exactly because the common things can be unknown ones for newbies, so any answer to help newbies are always useful. If the answers can help newbies to answer their questions, that are good. As expansion to newbies' questions, if answers are opened ones, newbies can move further and learning more from the answers. They can start with the answers and some given hints to search for more related things.