Typically Edgelit Exit Signs are illuminated with fluorescent lamps.
Replacing expired fluorescent lamps every year can be painful! and labour intensive.
A ladder is required and someone needs to go fetch it.
Accessing the burned-out bulb usually involves pulling the sign downward. Sometimes the sign is 'stuck' in its housing. Probably it has not been moved for perhaps a year. Humidity, dust, smoke effectively bind the sign in place.
What happens next?
Staff gives a 'mighty pull' on the sign and yanks it downward. The bulbs now can be replaced.
Over time, the housing starts to weaken and eventually the ceiling cracks around it. This requires patching etc... (ie: more work)
For New locations or simply to update the decor, look to the Edge-Lit Style Exit Sign.
It is very attractive....and extremely bright. Clearly outshines fluorescent or incandescent signs.
The purpose of an exit sign is to direct people in times of emergency.
Note that both Chicago and New York City have their own specifications for exit signs.