I was a student when I started EDCing lights. Mostly because about 80% of classrooms has no windows, and the emergency lights don't work [all the ones I tested doesn't]. The parking lot lights are only bright enough to guarantee you won't walk into a car, or a tree, or a stop sign, but does little for security. During my time on that campus my EDC was a 3D Mag85 [9AA to 3D adapter+WA1185 lamp stuffed in a maglite] with a streamlight scorpion as backup.
When I graduated I worked as a public library assistant. Night shift. Not all rooms have lights. if working in a public place taught me anything, is not to lay your fingers on any surface you cannot readily evaluate whats coated on there. Back room's just got enough florescent lights working to tell you where the exits are, unless you wear steel toe boots your piggies will thank you if you would shine a light in front of them.
Now I'm a small office manager whose evening job doubles as janitorial services. Same ordeal, check for spills in the stalls, rooms, hallways. Look around the porcelain for signs of incontinence, bad aim. Need a light to see streaks on he porcelain, not just the walls. Check the windows, doors, etc.