There’s been a bit of a change in the recommendation of the smoothed gray balance option since the release of Idealink Curve v1.0. It had been on by default and recommended for offset presses. With v1.1, it is off by default, and is now only recommended if the device has unstable or non-repeatable gray balance (I’m inferring this recommendation based on proposed amendments for G7 in 2008), which doesn’t always describe an offset press. An alternative to using smoothed gray balance would be to measure and average many sheets from the pressrun.
Although this option reduces the number points used to adjust gray balance, it may or may not result in “smoother” actual gray balance
My experience with smoothed gray balance with offset presses has not been positive overall, often actually introducing an imbalance in one area based on the wholistic correction curve it generated. So I would recommend that it not be used unless you only have a sparse sampling of the pressrun that exhibits unstable balance, and cannot average more sheets. In short, don’t assume that an imbalance on press equates instability and automatically click the smoothed gray option.