1. to me, and i expect most of players, didn't use supplement in the game much, as it occupy one slot is too wasting , if there was second circle like ACO, one circle is current stuff, like binocular etc alike stuff, second circle( my suggestion) is supplement, at least it can induce people to use some of them in the game.

2. if the supplement can have greater effect in certain region, this feature can also induce people to use much of them, like in snowy region, certain supplement will have greater effect then others would be a feature. in the same words, it may have somethings like above, to induce people to use some supplement would be a grreat things, although i am only using exp boost supplement mostly..