“Psychometricians generally regard IQ tests as having high statistical reliability.[9][56] A high reliability implies that – although test-takers may have varying scores when taking the same test on differing occasions, and although they may have varying scores when taking different IQ tests at the same age – the scores generally agree with one another and across time.”
“Clinical psychologists generally regard IQ scores as having sufficient statistical validity for many clinical purposes.[22][57][58] In a survey of 661 randomly sampled psychologists and educational researchers, published in 1988, Mark Snyderman and Stanley Rothman reported a general consensus supporting the validity of IQ testing. "On the whole, scholars with any expertise in the area of intelligence and intelligence testing (defined very broadly) share a common view of the most important components of intelligence, and are convinced that it can be measured with some degree of accuracy."”
None of what you cited has anything to do with sustained practice.
IQ tests are generally accurate across a large population because very few people are practicing them, not because practice doesn't improve scores.
If you provided widespread incentive for people to practice IQ tests like colleges do for the SAT, they would cease to be an accurate measure of intelligence.
You admit IQ tests are generally accurate, and I showed that SAT scores are strongly correlated with IQ. Thus SAT scores are also generally accurate. So what’s your point?
“Psychometricians generally regard IQ tests as having high statistical reliability.[9][56] A high reliability implies that – although test-takers may have varying scores when taking the same test on differing occasions, and although they may have varying scores when taking different IQ tests at the same age – the scores generally agree with one another and across time.”
“Clinical psychologists generally regard IQ scores as having sufficient statistical validity for many clinical purposes.[22][57][58] In a survey of 661 randomly sampled psychologists and educational researchers, published in 1988, Mark Snyderman and Stanley Rothman reported a general consensus supporting the validity of IQ testing. "On the whole, scholars with any expertise in the area of intelligence and intelligence testing (defined very broadly) share a common view of the most important components of intelligence, and are convinced that it can be measured with some degree of accuracy."”