There are online resources like testingmom that give out preparation questions for the gifted tests for admission into gifted programs.

Yes, unfortunately, test prep which provides familiarity with the types and formats of questions does not yield the most ACCURATE test result, although it may, in some cases, yield the HIGHEST test result.

After taking any particular IQ assessment, there is a required waiting period before that test may be taken again. Using a test prep which replicates the puzzles, challenges, and/or patterns of the scheduled IQ test is an unethical means of circumventing the interval requirement.

Acceptable IQ test prep and IQ test administration is covered in several old posts and discussion threads. Here is a brief roundup:
1) http://giftedissues.davidsongifted...._much_error_can_there_be.html#Post199479

2) Hoagies List of psychologists familiar with the gifted - https://www.hoagiesgifted.org/psychologists.htm

3) Test prep articles: one by Aimee Yermish, one by Nadia Webb - http://giftedissues.davidsongifted....t_do_you_tell_your_DC_be.html#Post174222

4) Full Scale IQ (FSIQ) vs General Ability Index (GAI)

BTW, here is a round up of older posts on many frequently discussed topics on this forum: http://giftedissues.davidsongifted....ps_of_links_on_frequent_.html#Post236361

Do you think that it happens a lot? For example, here?

It obviously happens enough out in the wide world that there are for-profit companies marketing it.

I have no idea how often it happens here, but I certainly strongly discourage it. Not unlike with the Varsity Blues testing scandal, it runs the severe risk of communicating to one's children that who they actually are is not good enough for their parents.

When my kids were young, I had parents ask me about the tests.... not directly asking for detail on the questions, but I suspect that was the intent. Then again, our school is rather hyper-competitive.....

I agree with aeh.

An old discussion thread reveals, unfortunately, that some may favor IQ test prep.
This post is part of that thread:
http://giftedissues.davidsongifted....erials_and_test_prep_for.html#Post210488

Operation Varsity Blues, the college admissions testing scam which became known to the public in March 2019, has had far-reaching negative impacts, including the faceless, nameless students who would have been admitted in the spots taken by students whose parents, aided by an admissions counseling service, participated in unethical practices.

When NYC used the OLSAT, there were practice tests handed out. The problem with the test is that they had teachers, retired teachers administrating the tests and there were several problems. These are not the standardized IQ tests, but it is an intelligence test that was used for placement.