I tested out a lot before I landed on my favorite 4 for profitability and ease of putting together.

Many agents offer a temporary agreement (Zillow uses 7 days) for a few showings or a single property, so you can test the relationship without a long-term commitment.

But you can run your own tests on this.

There are tests you can buy on Amazon, where you can swipe it on the walls to determine residue.

If you want more cash flow deals you may want to look outside of Boston and test out some new markets where you're hitting closer to the range of returns you're looking for. 

Either way, I wouldn't put the AirBNB terms of service to the test.

The challenge with the FHA guidelines is the self sufficiency test.

I wanted to burn down two houses on my 90 lot development.. not as easy as it sounds at least in Uber permit crazy oregon.. you needed lead and asbesto's test then remove those if they are present..

The way to find it starts with testing and challenging yourself and your system.  100% during hot time is one thing.

Ultimately it will depend on the property (banks perform stress test-debt ratio)-but I think 5 year term is what I found so far.