For example if investor A has 5 duplexes and investor B has 10 and they both have the same amount of money to spend on those units, that's 5 more roofs that need to be replaced, 5 more property taxes to be paid, 5 more sidewalks that crack and need to be replaced, 10 more water heaters to upgrade, 10 more furnaces that eventually go bad, 5 more yards to mow and do snow removal on, 5 more PM's if that's your thing, you get the point. 

The only similar experience I have is running a transit level and grade stick on building foundations and sidewalks. 

One of the buildings had some severe cracks between the sidewalk and the foundation wall.

Who sweep the sidewalks and street in frontbof their homes.  

Are you referring to Invest Atlanta’s plan to retool MLK with sidewalks and bike lanes?

Don't give them any money until y'all are standing on the sidewalk, the unit is empty, tenant hands you the keys and signs a 'good bye' document.

As for farming it to the tenants, I wouldn't do that unless you can clearly delineate whose sidewalk & yard belongs to whom, i.e. a side-by-side rather than up and down. 

@Alice Huang I had a situation with sidewalks where the old owner was notified sidewalk repair was required and failed to do it.

If you have a single family house, the tenants are responsible for cutting the grass, shoveling the sidewalks, etc. 

Snowplow service to clear the driveways and sidewalks and porch is one thing that comes to mind.