For me, most of my actual programming takes place in my head, writing the code is more the formality of expressing those thoughts. When focused I can go days without actually running any of the code I am writing and do not tend to debug that often.
That said, not seeing the code to be able to model it in my mind would be crippling.
True. Only when you have clear picture of a problem you can work toward solution. All of that happens in a head first. However, keeping track of 300 lines of code without looking at it is another thing.
Thank you for your comment :)