The US and UK governments have tried to help consumers make better decisions about warranties. The US Federal Trade Commission advises people to consider the likelihood of product failure and cost of repairs, for example.
Among all electronics, an extended warranty cost 24% of the product’s price on average. And customers bought warranties between 20% and 40% of the time.
There are very few situations where I’d recommend an extended warranty – I have one on my motorcycle because I’m mechanically incompetent – and am very happy to have my warranties doubled buy buying on a credit card.