Do bike commuters usually just have easy, flat rides on city streets? Or are hills involved?

I was thinking about this in terms of like, if you bike to work and have a tough ride with hills or whatever, doesn't that add a lot of time to your commutes? Don't you get tired/sweaty before even getting into work, then having to start the day tired?

Or working all day then having to struggle up a hill back home before even eating dinner?