There was a great UX principle around alternative mechanisms or backups. You can't have two rolls of toilet paper easily accessible in a public bathroom because

There was a great UX principle around alternative mechanisms or backups. You can't have two rolls of toilet paper easily accessible in a public bathroom because people will naturally use them up at a similar rate. You need to make ONE OF THEM more inconvenient to use, so that overall your bathroom experience remains useful and convenient. (You'll see this often with a sliding door between two installed rolls of paper, usually with a visible window showing the amount remaining) Introducing "artificial" inconvenience can be a very powerful usability improvement.