I think some good crossovers are just good progressives.
When my dance coach taught me progressives, he explicitly told me to put the free foot on the ice BESIDE the skating foot, not in front. The (previously) free foot then slides forward, while the (original) skating foot slides to the side. Later on, he said I could put it a little bit more forward by bending the (original) skating knee more.
This creates the tracing that you usually see in dance patterns, where the tracing of both feet don't intersect in a progressive.