Our employer allows us to work from home one day per week, with manager approval. My manager has approved us working from home, with one caveat. We are not allowed to work from home on Monday or Friday. This is designed to prevent abuse in the form of beginning or extending the weekend without using time off.
I like our policy and it seems to work well. I don’t take advantage of it every week. I’d say I probably use it about half the time. Over time, I’ve come to realize there are pros and cons of working from home.