As an European, I did never have any IQ test, nor I know anybody who (to my knowledge) was ever administered an IQ test. I looked at some fac-simile IQ tests on the internet, expecially Raven's matrices.
When I began to read online blogs from the United States, I started to see references to the concept of IQ. I am very confused by the fact that the IQ score seems to be treated as a stable, intrinsic charachteristic of an individual (like the height or the visual acuity).
When you costantly practice some task, you usually become better at that task. I imagine that there exists a finite number of ideas required to solve Raven matrices: even when someone invents new Raven matrices for making new IQ tests, he will do so by remixing the ideas used for previous Raven matrices, because -as Cardano said- "there is practically no new idea which one may bring forward".
The IQ score is the result of an exam, much like school grades. But it is generally understood that school grades are influenced by how much effort you put in the preparation for the exam, by how much your family cares for your grades, and so on. I expect school grades to be fairly correlated to income, or to other mesures of "success".
In a hypothetical society in which all children had to learn chess, and being bad at chess was regarded as a shame, I guess that the ELO chess ratings of 17 year olds would be highly correlated with later achievements. Are IQ tests the only exception to the rule that your grade in an exam is influenced by how much you prepare for that exam? Is there a sense in which IQ is a more "intrinsic" quantity than, for example, the AP exam score, or the ELO chess rating?
Short answer, yes you can get better at IQ tests by learning the common patterns and practicing the tests. Some people do so, and reach very high IQ scores. But there is essentially no reward for doing this, and thus almost no one bothers to do it. In the absence of practice, IQ is an empirically relatively stable metric which correlates with a number of other empirical outcomes, about as well as anything in the social sciences ever does.
This isn't a case where we need more research. This is a case where we have over a century of credible data(1) and the strongest theoretical constructs in psychology or any other social science. We just ignore the answers we have because nobody likes them. We'd rather believe that effort matters more than genetics.
(1) The US military in WWI and WWII tested tens of millions of men from broad swaths of society.