For all the people that spend hours farming something: There are 4 different stackable rare drop boosters in this game.

First is a booster (farmed from materials from the prison area)

Second is a Global Pathos (Alessandro's, at the bureau castle in the present after his bossfight)

Third is the consumable Windfall Stimulant (craftable)

and Fourth is high affinity Lise as partner (final partner bonus, but as all other non-"main" companions, she's unavailable in Luna Rapacis).