So, they make the process of being an investor seamless and you having to do nothing as they after you closing turn into you management company with a standard 10% management fee (which I am okay with). 

Is DIY cost segregation allowed?

Cash management, bookkeeping, bidding, people, etc.  

I have two LTRs out of state that are managed by a local, fantastic property management company.

Managing everything solo can be quite time-consuming, so collaborating with a reputable team is beneficial.

Is property management normally part of this arrangement?  

It's all pretty easy honestly.Vrbo and Airbnb makes it easy to manage.

I live about 1.5 hours away so I hired this project manager and a licensed contractor to manage the project.  

Not having to work in this example means having the 15 rentals producing enough cash flow to pay all their costs, including all 14 old mortgages and the 15th (new) mortgage that is refinanced each year.   

In this case, I've been a real estate investor and property manager for 18 years so I would be the one to find the properties.