Also, if you're dealing with a solo practitioner without staff, there's a constant struggle allocating time between technical work and customer service. 

Use the tax assessor's improvement ratio to determine how much of your purchase price was allocated to the dwelling structure and how much to the non-depreciable land.  

Jr ADU are only rentable with owner occupancy on the property.Other than that, the plan can work but if you have a high LTV loan, the property is almost guaranteed to have negative cash flow when properly allocating for all expenses.This negative cash flow situation will improve with time.  

My belief is if piti is $2400 and rent $3k, your cash flow is very small (maybe $100) when allocating for all expenses (vacancy, cap ex/maintenance, PM (even if self managing, allocate PM costs), misc (bookkeeping, share of umbrella, share of office expenses, rental tax, etc).Next fear is that in most markets a hands off ADU that cost $231k will be lucky if it adds $181k of value (negative $50k in value).  

And I would never feel comfortable allocating my portfolio based simply on splitting it across a  targeted number of deals (and/or trying to making all of them a certain % of portfolio).

Allocate cash judicially, sometimes it saves money to finance.

What is your experience with college rentals, how much do you need to allocate for repairs and vacancies? 

Say house was rented for 255 days and rest personal (70% house rented) then 70%:30% of property tax AND mortgage interest was allocated to Schedule E:Schedule A.2) The “Fair Rental days” & “Personal use days” are blank in Schedule E and (say) 70%:30% of property tax was allocated to Schedule E:Schedule A but 30% :70% of mortgage interest was allocated to Schedule E:Schedule A.Evidently Option #2 above is more tax advantageous (results in higher refund), but can it cause a problem with the tax man?

My goal is to allocate the capital I have into real estate.

The part of the gain allocated to investment is taxable.