The breakpoints have more to do with other parts of building codes. Wood framing is only strong enough to support three floors (unless you use cross laminated timber, which is a relatively new construction technology). Furthermore there are increasing requirements for fire suppression and accessibility as you add height. The breakpoints are basically either 2-floor duplex through quadplex that don't need elevators, or putting three floors of wood-framed apartments over a concrete or steel podium that contains commercial space and parking. Podium construction basically explains why so many 4 and 5 floor buildings get put up - it's significantly cheaper than the more expensive material required to make stuff strong enough for taller buildings.