in this matter of prayers the mormons appear identical to many fundamentalist protestants, at least as far as I can tell. a rejection of liturgical forms.
most of them, though, actually do have set prayers and other forms that could probably be called liturgical for want of a better word and i would be surprised if mormoans are any different. i have heard hundreds of people pray spontaneously and done so, and do so, myself, and find that all people have a set few things they say over and over again, so that they really do practice a type of repetitive prayer.
even people who speak in tongues repeat the same verbal patterns over and over again. the very idea of spontaneious and original prayer is a mirage, every prayer has already been prayed millions of times. Why not admit it and fall in love with the Catholic liturgy? which is precise, and wonderful?