Copy and paste
All my life I was working in CorelDraw and I used to some features that probably don't exist in Illustrator, but I'll try to explain my pain.
In CorelDraw when you have file with multiple pages, you can select object or some objects on one page, copy then and paste on the another page. And you will paste them on the same, exact place, but just different page. It's useful if you have to do same changes on different pages. But in Illustrator it just pastes on the middle of the screen. I don't even know when this way of pasting can be usefull.
Same thing with indesign.
