It has 3 units, an additional dwelling unit in the garden level, and 2 garage parking spaces (which I've come to realize are quite valuable where the property is). 

that we’ve learned in our 24 years, managing almost 700 doors across the Metro Detroit area, including almost 100 S8 leases:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+ (roughly 5% probability of default), zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680 (around 10% probability of default), some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

Your "backyard" is shared with 4 or 5 of your next door neighbors. 

More effective to door knock in some situations. 

Non-tangible property includes buildings, land or other inherently permanent structures.I get a lot of questions on which group specific assets belong in, so I put together a list to help.Non-Tangible PropertyBuilding (27.5 or 39 Year Useful Life)Land (Non-Depreciable)Paved Parking Areas (15 Year useful life)Swimming Pools (15 Year useful life)Fences (15 year useful life)Bridges (15 year useful life)Exterior Landscaping (15 year useful life)Docks (15 year useful life)Sidewalks (15 year useful life)Tangible Personal PropertyMillwork or decorative trimCarpetAir Conditioning equipmentShelving, cabinets and display racksAccordion doors and partitionsWall coveringsInterior landscapingNeon or other signsDecorative and business specific activity light fixturesGenerators, machinery and kitchen equipmentWindow treatmentsWhat other questions do you have regarding cost segregation?

Should I buy up as many cash flowing/appreciating properties for long term holds as possible to add doors to my portfolio (although, I haven't enjoyed being a landlord thus far...)?

I was aware of the egress requirement, but was not considering the door size or ceiling heights.

Quote from @Amol Kulkarni: HelloI have 3 doors that need to be managed in Jax and Citrus Spring.

a 2-car garage is a must-have for him, so it must be a townhouse or SF home. 

We wouldn’t want to resell within a year for the reason you mentioned, but we’re starting to think it’s a smarter strategy to buy and quickly fix up a duplex or more to first get our foot in the door.