At my previous employers, I didn't have that option. I remember I was in the middle of writing an important report and a supervisor said "you need to go out and do this." I asked when and he said "right now," and didn't care if I had my own deadlines to take care of. Where I was always experienced severe understaffing issues, and people were expected to cover for others. At my last job, when a certain section of the department was understaffed, I would be given work to do that I wasn't trained on, yet my poor performance on the work would be used against me during monthly reviews. I did my best and it wasn't enough.