After having visited the L4 leading Trojans ("Greeks") of Jupiter, almost a decade after launch Lucy will spend almost 4½ years moving on to the trailing L5 Trojans, 5 AU away. Is there a special window of opportunity of trajectories that motivates this huge traverse across the inner Solar system in order to fly by another asteroid?
Image is from a document if the Lunar and Planetary Science Conference 2016. The Lucy mission is commented by blogger van Kane here.