I use it all the time. Most times i simply use it to jump to the top or bottom of the file. Even if it’s just twice the length of the screen.

I thought QR Code follows a set rule for where the information is stored in the image. As far as I can see all of these have a custom set of rules, and thus need a custom reader to be able to decode. That's more of what I'm interesting in, but thank you for your answer!