I wondered the same many times. I think it would be a lot of pressure and for me that would mean mistakes.
I enjoy doing quilt tops and it would take the enjoyment out of the project. I'm not one that would at the last minute decide to make a quilt for a birthday or such, just a day or two out. Also, I need time to find a pattern and then to find the material to match the pattern. Guess I'm funny that way!!!!