What do most landlords of single-family homes do for routine maintenance and service? 

If I could teach someone the exact way I like to look at the numbers, they could simply plug the numbers in routinely until they came across something that cash flows with a ROI of 89%, which is the only way I am going to buy something (I kid). 

Routinely go to the property to check it out.

I typically check 3x a year at minimum, but due to family health issues and work, it wasn't possible to keep to my routine.

So, to answer your question, I routinely DO NOT meet contractors on-site once they're clear on scope and I trust them/have worked with them before. 

My routine usually falls in this order:Payoff HELOC, credit cards, hard money or private money used for real estate activitiesAsk investor friends/colleagues if they have any deals coming up that they would be willing to partner on Reinvest profits towards a 15% downpayment on a rental in desired farm area (I'm fine paying 5-10% below market value of a property if it is in my desired rental area and meets my criteria to cash flow)Lend private money out to other investorsPay towards principle balance on primary residencePay towards principle balance on rentals 

You would take the gross sale price and subtract routine selling expenses such as broker's commission, closing agent fees (escrow, title or closing attorney), recording fees, etc. 

Yes, on large commercial deals you will routinely encounter this.

Besides loss of control over when and how you make capital and routine maintenance expenditures, there's additional insurance you need to consider.For example, if someone seriously injures themselves within a common area, and the judgement is over whatever liability the association carries, YOU will get assessed your share of the extra dough.

Additionally, if you expect to replace something more than once every ten years, you can viably utilize the Routine Maintenance Safe Harbor and  expense the property in the current year.