Going over my DS's report I realized that only 7 out of the 10 sub-tests were used to compute his FSIQ. Is that typical? The three sub-tests that were omitted were significantly higher than those that were used. For example, PSI: coding, score 11 (63%), was used; symbol search, score 17 (99%), was not. WMI: digit span 10 (50%) used; picture span 15 (95%), not used. On VSI visual puzzles was also omitted but the difference between that and block design was only 2 point. Is it typical to omit these sub-tests? If so why specifically these? It certainly did not work to my DSs advantage...
Also, should I worry about these big differences in PSI and WMI sub-test scores?

Yes, that is the standard battery used to calculate the FSIQ. In fact, one is not allowed to make more than one substitution in the calculation of the FSIQ, and then only if the standard core subtest was spoiled in some way (invalidated), such as when we had a fire drill in the middle of digit span.

As it happens, there are actually many more subtests on the WISC-V than most students or their parents will ever hear of, as they are not part of the standard battery.

The FSIQ subtests were selected based on their psychometric qualities--i.e., statistics regarding which ones were the highest quality contributors to measuring general intelligence. The two cognitive proficiency domains each contribute only one subtest because higher-level reasoning is considered to be more important than rote speed or memorization. Likewise, visual spatial skill appears to be less of a factor in academic success than either verbal cognition or nonverbal abstract reasoning, which is why VS gets one subtest, and VC and FR each get two.

The selection of which subtest is included in the FSIQ is mostly not up to the examiner (except in the type of situation noted above), and specifically is not intended to work to anyone's advantage or disadvantage.

Should you worry about the splits? Not necessarily. I've discussed elsewhere that there are several non-alarming explanations for these splits, as well as others of varying degrees of functional importance. CdVC). Do you have any IRL concerns regarding speed or memory, or inconsistencies in those areas?

Thank you, Aeh, for the post, very informative.

I do not have any particular concerns, I am just trying to understand the scores and how they "explain" my kid. He's very puzzling to me. He scored considerable lower than his sister. And yet his interests, need for knowledge, reading level and speed are way beyond hers. He is the one more difficult to parent and keep not bored at school.

He missed the official IQ cutoff for a gifted school and I really don't know what to do with him. He is starting to disengage in a regular (accelerated but not gifted) classroom...

If you'd like us to take a look at the complete set of testing data and give some feedback, feel free to post more. If you're not comfortable with public posting of that much private data, I'd be happy to give you some of my thoughts on pm.

Thank you so much. I PM'ed you with the scores.