One Set of Pipes or Two?
First, a caveat: for the record, I’m never in favor of winterizing a home, even one that’s vacant, even in Minnesota in the winter.
In my experience, it’s almost always more cost-effective to empty such a home, move any to-be-disposed-of personal effects into 
storage, and expeditiously get the home on the market.
With the heat on.
Estate Sales
Of course, that’s not how the world works, especially when the home is the subject of an estate sale, and multiple actors (some legal) are involved.
So, to keep utility expenses down and to minimize the risk of a catastrophic pipe freeze, it can (occasionally) make sense to winterize a home.
Hot Water Heat vs. Forced Air
The more straightforward case is a home with forced air heat.
Then, all that’s needed is to drain the water out of the plumbing pipes.
The more complicated situation is when the home has hot water heat — that is, it has a boiler and radiators.
Then, the heating system pipes must all be drained as well as the boiler.
Cost-Benefit
So far, so good.
The problem is that once the boiler has been drained, mistakenly turning it on will destroy it (not to mention risk starting a fire).
Think of it like starting a car engine with no oil in it.
While that risk can certainly be minimized, the high cost of a mistake — not to mention the expense of starting the heating system back up — can militate in favor of simply turning the heat down temporarily to 55° or 60°.
See also, “Q: What’s the Opposite of ‘Winterize’?”
P.S.: I can’t prove it, but I’d guess that “For Sale” homes that have been winterized fetch at least 5% less.
That’s because buying a home is such an emotional experience, and (almost) nothing kills that emotion faster than seeing your breath inside the home (never mind outside — it is Minnesota, after all).
