Zoning generally requires egress be possible from every room which is a sleeping quarters (or living space like living room) via a window or door to the outside

Zoning generally requires egress be possible from every room which is a sleeping quarters (or living space like living room) via a window or door to the outside. I’m not sure that a door to a common hallway would be considered legal egress. Further, even if it was, this would require each sleeping quarters within your apartment to have an emergency exit door to the common hallway, in addition to the door within your apartment. This would be pretty loud and unattractive. Another zoning concern is that there is generally a rule like “every area of apartment must be within 30 feet of door/window to outside”. So if you create these deep cavernous apartments you won’t be able to meet this rule either. For example in NYC, every room needs two forms of egress. Bedrooms this is the windows + door back to rest of your apartment. Living areas this is windows + door out to common hallway. It is illegal to create a room that has only 1 exit/entrance. The concept here is that in the event of a fire if your 1 & only exit is blocked you are dead. Similar rules apply to why in most jurisdictions you cannot legally finish off your basement unless it has sufficient exits directly to outside / windows big enough for a firefighter in full gear to fit through. This limits many existing basements for conversion depending on their depth as its hard to retrofit these into existing foundations..