I think some of it may have to do with how your brain works. I've very math and chemistry oriented, so weighing and percentage loss over specific days really works for me. On the other hand, when it comes to artistic talents I'm not qualified to draw stick figures or play Pictionary. So even though I'm very good at visually estimating percentages, and even though the reference pictures of air cells are very good and it seems obvious, when I candle my eggs my brain can't figure out how what I'm seeing applies to the air cell pictures, and it just doesn't work for me. Circular frustration!! I think it's more difficult for me to mentally translate between 2D and 3D than most people. Maybe if I had a 3D model with air cell lines drawn on it I could use air cell size more easily. I know, it doesn't make any sense (to people with any artistic talent). Kind of like it doesn't make any sense to me that some people just can't do basic algebra. But it's all about how our brain works. I'm just glad there are two different methods, and that at least one works for me!! Maybe with more candling experience, I'll figure out how to do both..