The moment a sofa throw actually clicked for me was over a navy sectional that came with the apartment, the kind of dull gray blue that made the whole living room feel like a waiting room. I draped a rust orange throw over one arm, just to see, and the whole couch woke up. Nothing else changed. That's the part people underestimate, how much one layer of color can do when the furniture itself is stuck being neutral.
Where a throw falls short is thinking it can fix a sofa you actually hate. If the shape is wrong or the fabric is already worn through, a throw is a bandage, not a cure, and it will slide around annoying you every time someone sits down wrong. It also won't save you from a truly chaotic room, if you've already got a patterned rug, patterned curtains and a loud accent chair, another pattern on top is just noise. Use color there instead, a solid in a shade that pulls from everything else in the room. On an ordinary room, a throw works best doing one of two jobs, either it's the boldest thing in there, a deep emerald or a burnt orange against a plain sofa, or it's the one calm note in a room that's already busy with pattern elsewhere. Think about what it sits near, a striped pillow, a wood coffee table, a lamp with warm light, because the color reads differently under a yellow bulb than it does in daylight, and you want to check that before you commit.
As for wear, a good throw earns its keep fast. Mine has survived red wine, a dog who treats the couch as hers, and a move where it got stuffed in a box with the shoes. Wool and cotton blends hold up best, they soften instead of pilling, and a wash on cold with a gentle cycle keeps the color from fading into something sad. Cheap acrylic ones look fine in the store and then go thin and bobbly within a year, so I stopped buying those after the third one fell apart. Fold it instead of balling it up when it's not in use, that's what keeps the edges from looking tired. A year in, a decent throw should look softer and more lived in, not worse.
This is for a home where the furniture is fine but boring, and you're not ready to replace the couch, just wake it up a little.