Lucian players and wasting mana.

Is there some unwritten rule I'm unfamiliar with where if you play Lucian it states that you must use every ability possible and waste your mana as quickly as possible during the laning phase? Without exaggeration, EVERY single Lucian I've ever support has used every ability on even single minions. I've seen multiple different Lucian's use his Q on single castor minions (you know, the ones worth 18 gold). I understand that his passive grants you two auto attacks quickly after an ability, but it really isn't worth it.

Most of the time this happens, is early game, when the minions are fighting each other and there's no real pressure at all. What am I missing about Lucian?!