Al
You are correct, that was slip on my part.
But having said that, its not actually that simple, you might need many more notes. In full keyboard mode, every note counts across the whole keyboard, and one of the notes is certainly going to be a melody note that may not be a part of the chord. So its actually likely that only 3 notes would define the wrong chord. Even 4 or more notes may still result in the wrong chord being interpreted. That is one of the issues with full keyboard modes, especially for those people who are following a simple piano manuscript. AI works a little better because it also uses the previous chord sequence information to deduce the likely correct chord. There is no downside but some upside in selecting AI, and this is what people should use.
In general, if you use plenty of chord information in your playing, it will work pretty well, even for advanced chords. Even if the chord is a little 'off ' you will be playing full chords on the selected voice, and errors will not be noticed.
Mike