A lot of small trash—tissues, wrappers, used sticky notes, thread pieces, cotton pads—ends up on side tables, in drawers, or stuffed behind cushions simply because there isn’t a bin nearby at that moment. You think, “I’ll throw it later,” and later never comes.
A small, decent-looking bin in key rooms (living room, study, kids’ room, bedroom) gives you zero excuse to leave rubbish lying around. The distance between your hand and the bin is so short that you’re more likely to use it immediately.
At the end of the week, you’re dealing with a few bins to empty instead of walking room to room gathering clutter from random surfaces. Mentally, rooms feel cleaner when you’re not constantly seeing “temporary” rubbish everywhere.