In the 3 months that I've owed it, I have had the sewer line cleaned out twice.

Turnover cost (cleaning and repairs, but also typically 1-2 weeks of turnover time with no rent -  it’s possible but very rare that you can turn over in just a day or two, even in a strong rental market), then there will be service calls/repairs/appliances replacement and maintenance, flooring, painting, etc.  

Be sure to clean window sills, inside the windows and the floors under windows and also exterior doors, Each inspector has their hot buttons.

You might have 8 months of collecting "profit" and then have one bad incident that demands all of that "profit" and drives you a couple thousand more into the red.On a property that's generating a healthy $500-$700+ profit a month, I'd either be driving it back into the property to fix any immediate cap ex threats or saving half for a future investment, and half for padding the emergency bank account

You could just put in regular machines and not give your tenants access...of course, they won't be thrilled the first time they run into you with a basket of clean cloths under your arm.

Suggest that their part will be to have the unit in "show-ready condition" (clean, uncluttered) and to accommodate showings. 

A good GC would have multiple trades working at same time and site should look pretty clean.

Replaced the windows, HVAC, thorough cleaning & paint What was the outcome?

We put in new floors, paint, fixtures, and cleaned up landscaping.

If I was renting and the landlord said "The dryer repair person will be there at 1:00 to fix it" It would not be outside the realm of expectation on my part that "Cool, I'm working at that time they can do whatever they need to, I'll just make sure I clean my socks off the floor".