I have made many mistakes while making my models. For my house in sketchup, the wall would disappear! Then when I would try to export it in Blender, the windows on the beck would give me trouble. Then with my model I had to try so many times to make a spin and it just wouldn't work. I have so many extra files from when I would try to make a spin with my sculpture. The thing with 3D modeling with these computers is you have to have patients, you can't always have the best model or best example, you have to go at your own pace and challenge yourself slowly to make your model and portfolio have what it needs.