I see that this passive part of REI is crucial as you mature in your porfolio.Since I have a very busy full time day job, I'm juggling the time vs. money vs. excitement for REI strings and sometimes failing to find that right balance.   

Especially if they aren't paying market rent.Some landlords will overlook everything as long as the check shows up...... in my opinion that is a long term way to fail.

Oops, I did fail to mention.

Yes, @Ben Walker what most fail to realize is that what you described most likely is a Security and thus you must comply with all of the Federal and State securities laws.  

No1 reason many people fail or quit is that they never challenged their conventional thinking or how they viewed the world first before jumping into REI.

The billboard would remain the property of Lamar unless you terminated and they failed to take it.

I bought a property last year in WA  state and the lender failed to foreclose for 10 years.. and the lender just mailed the owner their deed I had never heard of that before I guess there is some statue of limitations as to when a mortgage or deed of trust needs to start an action once default has occurred. 

If they failed to collect them, that is their problem (and their job). 

Which 95% of everyone fails or gives up in every field (wholesaling, investing, rehabbing, selling, development, etc.)

Sorry, but there is a reason so many people fail in business and it is because they believe and trust the wrong people to help make decisions.