Personally, I know how to replace a toilet in my rental units, but I rather pay for it at this point and focus my time on family or building my business/portfolio versus getting lost in the details. 

(There will be things that need replacement after year 1)  Consumable supplies (coffee, toilet paper, soap, trash bags, etc.)

Turned out toilets in both bathrooms were essentially running non-stop, plus a couple of other minor issues.

And of course leaking toilets and dripping faucets will affect your water AND sewer bill, so you really need to inspect at least annually, and watch the usage very closely for sudden large jumps that need looking into right away.You should be able to review the past 12 months usage, possibly longer, to get a good starting point.

LOL.. you could have renter or lease squatting that takes money and time..

Fixing toilet emergencies at 3am isn’t appealing to most people.

Super closeups of the wall above the toilet, very dark and grainy photos of long hallways, or, our fav, a pic of a pic on a computer screen! 

Check your local laws, CLOSELY, but I would consider 5 degrees/no heat an emergency, and would take ALL measures necessary, with witnesses, to protect my property. this would include draining the waterlines and entering the unit to blow the lines down if they are not frozen already, and putting antifreeze in the toilets.

Call me crazy, but I’d prefer my tenants let me know when a toilet is leaking, sewage is backing up in the basement, or the furnace went out when it’s 0 out.

Somebody told me that it's not uncommon that during a flip, especially if it's a mediocre job or contracted out, lots of debris and stuff will get flushed down the toilet or down the drains from sinks or bathtubs, and that can cause a backup quickly for the buyer, especially with old deteriorated cast iron pipes.