You are right that working within a time limit will not give me enough space to really get better. However, I enjoy the competitions for a number of reasons. First, they force me to do something I would not otherwise have done. For instance, working with a limited space and palette as in this piece. Second, it is fun and encouraging to compete with others.
The obvious compromise is to keep working on a piece for personal gain, even after the competition is over. And this is exactly what I will do. Also, I am working on personal pieces along with the competition ones.
Updated paladin:
I initially was trying to make some sort of saturation gradient in the sky, but the dark yellow just didn't mix with the grays. So, I made some hills behind the mountains, not sure if it improved or worsened the piece. I added some more highlights like Souly's edit shows. I got rid of the things on his back, I don't know what they are at all, I just put them in there for completeness.