When I was still in the grade school, the 8th grade I think, a Civil War reenactor came to talk to from the historical museum. He said that during the Civil War there was a shortage of paper to write on. (But ink was pretty affordable of course.) So the soldiers would conserve on paper by writing the letter as usual. But then they'd give the paper a 90° turn, and write the rest of the letter. He said when you do that, it really doesn't matter that you're reading text written over other text. Because your brain filters out the information it needs then. I guess that might be true. I was also thinking at the time. If they turned the paper upside down and then wrote the rest of the letter, they'd be writing lines of text thru lines of text. Basically crossing everything out, if you visualize what I mean. That might have had something to do with it too.
