In the Northeast, gc supers are always monitoring the color of the turf, watching out for "off color" which is usually a light blue tint to the turf. You can actually see when the turf is beginning to suffer moisture stress by visual inspection and monitoring evaporation and wind rates. You should syringe only if needed, only on parts of the green that need it.
The turf doctors always say "water to field capacity" which means irrigate to a point that the soil cannot accept any more water. Infrequent,deep night irrigation is always better than syringing, assuming that you have the grass types and green construction that can survive a windy, low humidity day. If not, its time to syringe.You can't really assume that a USGA green will require more water but it fair to assume that old, push up style greens are constructed with loamy, native soils and they really retain water and require less irrigation than the sand/soil based USGA specs. You need to evaluate each green to determine what is field capacity.
As for humidity, you can't assume that high humidity requires more water, if fact it requires less water because the evaporation rate is lower although high heat and wind are other factors that can dry the course out. In the Northeast, the worst days for water usage are in late May, when low humidity and high winds combined with short roots to really dry out the turf.
To Eric, You are right, Poa greens are a whole different animal, they love/need syringing.