When I setup a new browser, I always delete all the default search engines and install DuckDuckGo, Ecosia, Qwant and Startpage. If I’m looking for accurate results, I always use 2 or 3 of these. I can’t say I consistently get better results using one or the other.
Only on holidays. If I pick up some furniture, I don’t bother, but when I’m driving for one or two days straight with 4 people and luggage in the car, yes definitely. It helps that I can check/adjust my tire pressure where I wash my car every two weeks. I’m really particular about the handling of my car and the tires I drive on, so I’m always on top of the correct pressure.