No one, including me, would get bored or tired of reading a post that contains helpful and constructive information and knowledge. So as you said, it's not about the length of a post being created but it is the quality it contains. Even very long posts are read with interest in many sections of the forum but only if they have some meaning and are contributing to the discussion. Someone would surely ignore a post being unnecessarily long while containing nothing useful and read-worthy.

It's a common misconception among newbies that making long posts earn you merits and it's because they see long posts from senior members getting a lot of merits but they fail to determine the fact that those posts are of high-quality and aren't some gibberish written to unnecessarily prolong the post.