We did inspections every 6 months (26 unit building), and would check smoke detector batteries as well as look for leaks or running toilets.And if the water bill went up significantly, we'd do additional inspections, looking for the inevitable running toilet.Next best option is to use month to month agreements, so if you suspect a unit is going crazy with the utilities, you can get rid of that tenant.  

Fuel with 4amp/hr battery will last longer than the sears impact driver itself.

What you should be fearing is the reality of what could happen:Say you forget to check the smoke detectors, or forget to put them up in all the bedrooms, or years go by and the battery dies-- huge fire breaks out, destroys you place (if you don't have insurance, it would be a total loss!)  

If you start doing things like this, you’ll be receiving calls for a plugged toilet, replacing batteries at 3 am in a smoke alarm, a noisy neighbor, etc.

I also have an abundance of detectors of both types, and I hardwired them so no lapses from forgetting to change batteries.

Technically you can make an excuse like check smoke alarm batteries, replace furnace filter, etc., but a determined tenant could push back on that too and say that they will tend to those things. 

First let me say this- if it is more than replacing light bulbs, batteries and filters I don't let tenants touch anything.

If you keep the property up, and do inspections every 6 months, change smoke detector batteries, meet codes, etc., I can't imagine anyone having a multi-million dollar successful suit against you.  

I used to be an onsite manager less than 6 months ago in CA so that would be my feedback.the other stuff is not that important, it won't net much gain in rents.your annual maintenance is critical on each unit  - caulking, changing flappers and batteries on smoke detectors, co detectors and changing air filters.

The Leafs are pretty cheap and their batteries last a long time and are not that expensive to replace.