They're all very similar in my opinion, and do about 90% similar functions.

During your initial walkthrough, inspect the property for any major issues such as structural damage, roofing problems, plumbing, and electrical concerns, while documenting all cosmetic and functional issues with detailed photos and notes.Once you confirm the property’s potential, finalize your ARV and calculate the repair costs using either a reliable estimator or insights from contractors.

This is a logical function of market forces. 

The function of this guide is to get the reader up to speed quickly on the neighborhoods so you can invest in neighborhoods that meet YOUR investing criteria.

Another issue I see with older homes is the layout and functionality is tough to manipulate even during a full gut.

Quote from @Zachary Deal: One thing to keep in mind if you are doing this is that you are likely to create "functional obsolescence" which could mean you are not able to get a new loan against your property and it can be difficult to resell as well. 

OK Thanks Chad.. yes now that you clarify that and I also work in the low value asset sand box but only to Investors who have money to turn them around I would never count on those owner occ's to cure at least at any large % to easy to  walk  and the properties as you mentioned many will be functionally obsolete and economically obsolete so they turn into your basic zombie house that local wholesalers go for ..

Secondly, the appraisal often notes functional obsolescence because of this and a lack of a common area.

ADUs can significantly enhance your property's value by adding living space that can be used for rental income or as additional living quarters for family members.The increase in value from an ADU can vary widely depending on several factors such as the size, quality, and functionality of the ADU, as well as its integration with the main property.

There are some important factors that you need to take note of with regards to the 1031 exchange or the Tax-deferred exchange: •One important requirement you need to have if are an investor and you want to take advantage of this 1031 Exchange is that the property you are selling should be significant when it comes to trade or business functions that are beneficial for the people as well as for the government.