This means that I tend to do a lot of testing of these elements, and also I put in dummy elements while waiting for textures or sfx or whatever to be made to fit. The best part is being able to see a joint vision come to life. There comes a time when all the parts start to take on a life and become a whole. That is a very cool thing to experience. The hardest thing is knowing when to stop.
Most level designers are their own worst critics.
We know all the flaws of our work and could tweak forever. I'm a chemist by education. Level designing is a good release for my creativity. At the same time, I believe my technical training has been useful in problem solving when setting up complex entities. I made some doom2 levels.