Essentially choosing how much shadow is important in a given scene.
Where detail becomes acceptable on film is technically important, what tone we actually put there is subjective.
My thought is that once I've pegged the shadow point I want, that the faces and other tones, will fall properly in relation to each other. Essentially one specific enlarger exposure would place the faces properly in relation to each other.
Shaded faces will look shaded, those in full sun wil look like they are in full sun.
Let's assume for a second that the fair is the setting for a portrait.
The setting/background could be made to fall in a very believable manner from shade to sun, the challenge in camera becomes how to fit/light/isolate the main portrait subject in that scene in such a way that looks natural.