At a loss for hovering over UI elements, should I have a controller for the entire screen, or each element have their own?

I'm working on an items atm and got to the stage where I'm creating item drops. For dragging and dropping I've been using a single controller and initially did the same with hover, but I have no idea if I should stick to that method.

Think Diablo/Path of Exile having dozens of items on the floor, should each item box have it's own interface for hovering? Or is one controller for the entire screen better?

I'm mostly worried on the one for the entire screen because the hover happens over every single UI element that is raycast-able, but I'm not familiar enough with what happens behind the scene to know if it would be better for each element to have it's own controller instead?

Any help is greatly appreciated, sorry for the trouble.

As a bonus question, anyone know what I should be looking into to make the item boxes UI not overlap and instead fit around each other?