When I was doing a secretarial course which included learning to type on a typewriter, I did one of the specified exercises, which involved formatting a long business letter. The teacher said that I had done it well, but that it should not have been continued on the back of the paper, but on a second sheet of paper. I have always thought that was idiotic. What a waste of trees. Blessed Mary MacKillop of Australia had an interesting approach. She wrote her letter down the page (in the portrait position) and then turned the paper to a landscape position and wrote the rest of the letter across it! This would have been a bit of a problem for the reader, but she was a very neat writer and it could be read. Later on she also learnt to type on a typewriter. No doubt she did her double writing technique on the back of the paper also.
She was a greenie before greenies existed! Now I hear that the USA wants to save money in order to pay for their immoral health scheme, (which has everything tied to abortion) so one of the government departments there is saving money by using both sides of the paper! It is amazing that it took them so long to think of something so simple!