A lot of the requirements make sense in bigger buildings. It's not easy to evacuate a large office building taking up a city block using only ladders. And some

A lot of the requirements make sense in bigger buildings. It's not easy to evacuate a large office building taking up a city block using only ladders. And some of it is reactive; for example, there is a distance separation requirement for stairwells, because during 9/11 the three North Tower stairwells were only 70 feet apart and enclosed only with gypsum, so they were all severed on impact, dooming the people above the impact zone. But none of this is really relevant for a building with six floors and 24 units total. The American city topology is basically office towers surrounded by single family homes; in the midcentury we demolished a lot of the in-between building stock, which is now referred to by urbanists as the "missing middle". Compare this to Europe or Japan which is largely buildings in between those sizes.