On this tour when they use AOD as the intro song, Tico and Hugh get left off as there is no place in the middle of the guitar solo to intro them, i've never seen nor heard Jon leave anyone off when Shout is used as the intro song, but I have been at quite a few shows where they don't do intros at all, and sometimes Jon takes a moment throughout several different songs to acknowledge one band member or another. I do think intros get left off if there is a time constraint, but then there are nights when Jon will do a very long, involved intro segment for the band, it seems to depend on how he feels.