It happens frequently that I am supposed to cover for a couple of co-workers during their annual leave but I would have no notice of it. I would find out on their first day of leave for example that I am supposed to step in. It has also happened that I was waiting for a piece of work, then chase it in the afternoon and I get 'sorry I am off today, will send over later today'. No out of office notification and it would be for work that's due on that day and could not wait.
A few times I raised it with my boss and she acts like I am the problem. Tbh she is one of the culprits too. She'd be on a business trip Mo-Fri, but will tell me Thursday night or Friday morning to cover for her on the Friday as she will be mid-air. She would have known at the start of the week or even weeks before and could have given me heads up. This is important as I am busy myself, some work can wait and other work cannot and I would plan work differently had I known.
I also feel totally disrespected when they do that and it stresses me out as it's like a bomb is dropping and something urgent is popping up that doesn't need to be urgent.