These shortcuts are not time savers, they are deal killers, or rationalization justifiers. 

These are the two ADU / DADU markets where investors should be focused - not just because of friendly ADU/DADU regulations, but also because of the strength of the rental market in those cities.There are some absolutely killer investing strategies you can build around this (SFH + DADU + Opportunity Zone Fund for instance, which would make all of your cap gains tax free), and DADU costs in particular, although high, are coming down.