My mom used to manage a barn with a few boarders and did not have any set times. She would get there by 7:30am and feed, 6:00am in the summer because she didn't have to take me to school. She normally "closed up" at 6:30pm in the winter and we would leave, but the boarders were free to stay or come whenever as long as they put everything away. In the summer my dad would bring his spotlights so everyone could ride after dark and a normal day for us was 6am-9pm at the barn. There was a gate to keep unwanted people out and loose horses in but it was not locked because of emergencies that could occur while nobody was there.
Now I am limited to daylight because the horses are at my house. This summer I want to use our lights to be able to ride later because it is so hot during the day and the arena has no shade.