Are standard IQ tests really accurate?

People often wonder why some people who are bright in class don't do so well in IQ tests. On the other hand, those who don't do well in class may excel in IQ tests. This doesn't mean that IQ tests aren't accurate. It only means that some people are smarter when it comes to logic and reasoning, while others have better memory skills. Because school examinations cover such a wide array of topics, it is difficult to judge the overall intelligence of a person. Students may do well for one or two subjects that they are exceptionally good at, while scoring lower marks for subjects that they are not so interested in. There are people with low IQ test scores that do very well for their exams and the reason behind this may be just that they have studied harder than others. This has nothing to do with logic and reasoning skills; it is just a matter of determination and hard work. Therefore, the definition of intelligence is a continuous debate.

Any thoughts on this?