As a teacher, I think it's important to share our tricks of the trade with each other. I'm an older teacher. I graduated from college in the early 90's and I admit I took a class where they showed us how to load the filmstrip on a projector. I am one of those teachers that collected the teacher worksheet books from the local teacher store and did my student teaching in a school that still had the mimeograph/ditto machine in the workroom. (and yes, the teachers used it....and so did I.)
With the birth of the internet and TpT, my teacher books were used less and less, but I have to admit I still use some religiously! I love them and they work well for me. Maybe you have some favorite teacher books you still copy from also.
When I first started teaching, I would forget which pages I had already copied from. My students would tell me that we had already done that page six months prior. (They never forget anything like that, but they never remember their addition facts do they?!?!?) So I developed a system. I put a post-it note in the front cover each year (or use the same one if I only copied a few pages the previous year). Each time I make copies from the book I write down the page number, that way I don't repeat any pages. Some of my books I skip around in so this is very helpful! Just a simple easy trick that helps a lot!