In the sales models, light switches should be wired so that the lights are always on to prevent people from turning lights on and off as they walk through the models.
This approach accomplishes two things.
First, it prevents people from inadvertently leaving dark pockets behind them as they tamper with light switches while walking through the sales models.
The builder wants the sales models bright, cheerful, safe, and inviting, by having all interior areas of the models well lighted.
Second, the sales people do not need to constantly walk through the models turning lights back on.
The best approach is to have a master switch located in the sales office, whereby sales staff can turn on all of the designated lights in the models at the beginning of the day, and turn off these lights from the sales office at the end of the day without having to physically walk through the models turning off lights.