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What you describe here is pretty commonly seen for apartments, dorms, and hotels. The fire code does not require system smoke detection devices inside residential apartments or dorm rooms. If such detectors are to be installed, they have to sound only a local alarm (usually from a horn built in to the smoke detector) and show an abnormal condition at the Fire Alarm Control Panel (FACP), but cannot set off the building signals. Sometimes they are allowed to be self-restoring, however this is uncommon. In most cases, though, they simply install a 120V smoke alarm like in residential homes.
Fire alarm systems are required in the common areas no matter what (or what you called the “impersonal” areas) and additionally, an audible or audible/visual signaling device is required inside each apartment or dorm that sounds with the building system. This is why you have horns in each room of your apartment. Older buildings relied on the signals in the common areas only, as the horns in the apartments requirement had not been implemented at the time of construction.
There was one system I had seen that had a high end addressable system where they installed smoke detectors with sounders in every bedroom and hallway outside the bedroom in each apartment. The FACP was programmed to sound only the sounder bases in that room and alert the building personnel. They also had an addressable control module (basically a small signal circuit that can be individually controlled) wired to turn on strobe lights in the rooms too. The smoke detectors in the lobby, hallways, community rooms, and shared spaces were programmed to sound everything in the building. It is a very complex system and works quite well for the purpose.
So yeah, your setup is not excessive, it is what is required by the fire alarm codes.