Even at the scheduled times it is tough to get neer them because of the crowd. I wouldnt waste the time if I were you.
P.S. I am suprided tho that more people dont like MGM. With Rock N Rollercoaster, TOT, Indiana Jones (still the best show in all of DW) and other avg, rides (Great Movie Ride, Lights Motor Action, Star Tours). I think it at least warrents a half day...oh well, to each his own.