So at your work you can get assigned a project then the day before it’s due just use your time off, have the project remain incomplete and face no repercussions?

How is that at all similar to what happened here? Sally took 1 hour a day off. If management is so incompetent that they can't correctly delegate an hour worth of work that's on them - not Sally.

And you don’t see how it’s a big deal to do that when it’s you and somebody else assigned to do the project and now that person has to do the entire thing and stay in overtime to do it or else presumably you’d both get in shit?

No because that's how time off operates. Again it's on management if they are so incompetent that having one person taking time off disrupts an entire project. Especially only an hours worth of time. Are people never allowed time off because someone is always going to be burdened when they do? I'm glad my supervisors don't think the same way you do.