Should the front door in apartment buildings be locked at night or not?

Many house rules in apartment buildings specify the front door to be locked between 10 p.m. and 6 a.m. A locked front door protects against burglars and other unwelcome guests. On the other hand, the escape route / rescue route is blocked in the event of a fire and guests can only leave the house late in the evening if they are accompanied by the host.