More likely, he is hoping to use the extra time to collect more rents and thus more fees to generate the funds to pay his owner clients:(

How do you actually strike from out of state in a timely manner?

Thank you again for taking the time!  

However, they spend a ridiculous amount of time for 1-2 deals a year.

With an owner-occupied loan, you can buy a house with 0-5% down and get 30-year fixed rate financing so you're not dealing with adjustable rates if rates go back up and not dealing with a balloon payment in 6-24 months which is plenty of time for an experienced investor but not a whole lot if you're new. 

But do you think that 4-5 years is not a window enough of time for them to recover? 

Take your time and don't rush into anything.

Bonus depreciation is a one-time election per asset at the time of acquisition.

@Bradley Buxton makes a very good point to make sure to do your due diligence as you won't be an owner occupant like your in-laws.Last bit of advice: Because this is a friendly deal, you want to take your time to make sure you structure it in a way that maximizes tax and cashflow benefits for both parties. 

The time of DIY partnership returns has passed.