It's true that posts that are too long can discourage many members and prevent them from reading them, but it is also true that shortest ones can go unnoticed, especially if written by newbies.
There is a healthy in-between, not too short nor too long, but in the end everything has more to do with the quality of your ideas rather than with the length of your writings.
Nice one, when i signed up i used to write length post, as newbies as i continued to learn and read other people posts, i adjusted my writing. The most important thing here is the quality of your post not the length of it, people with short and quality post will have merit on their post while you with length post will not even have a reply from your post.
The only way to grow is to keep reading post from legends, and hero members, at times read from those on same level with you that is getting merits on their posts. We learn from the best, that is what has really help me on this forum.