How do visualisation meditation practices relate to insight?

A while ago I attended a Tibetan Buddhist group. They were very nice but I just couldn't get on with the visualisation practices. I find it reasonably clear how mindfulness of breathing becomes an insight practice and metta bhavana. But I just couldn't see how an intricate visualisation practice would lead to an understanding of conditioned existence, suffering, no fixed self or any of it really. How do visualisation practices relate to insight? Additional detail - the practice involved the Buddha in a bright blue sky on a throne and I remember there were snow leopards under the throne and light was going out of the Buddha.