Just because you eyeball something doesn't mean it doesn't fit into some sort of mathematical alignment. It's like, you can play drums in 4/4 at 120bpm without a metronome and think it sounds like you're playing in time, and maybe you are even though you didn't use a metronome or check against a metronome to see. Do you see my point? There isn't a mysterious aspect to art.
There is a reason things look good, and that reason can be scientifically measured, regardless if you want to believe that or not. It's just like we can determine whether or not someone is singing in key or playing in time. It's not an opinion. It's not like: well, just play and sing what you think sounds good. You can do that and maybe you'll be in time and in key, but there is a way to check one way or another.
The reason I mentioned the grid system is because I knew I would get these sort of answers. I want a way of doing this that can be measured and I don't see why using a grid system wouldn't work, so that I can know for sure that there is some underlining mathematical measurement that the size and placement fits into.
I can eyeball it and make it look good. But I want the precision and certainty of being able to check it, just like I can check a piece of music to see if all the beats are in time or notes are in key.