Ceilings are ceilings relative to the tester age. The 19 point scaled score is derived from the raw score for a subtest based on the normal score.
As a pure example: A sub-section may have 40 progressively harder questions, an eight year old may hit the ceiling after getting 23 correct generating a scaled score of 19 (which is 3 standard deviations above the mean.)
A fourteen year old may get a scaled score of 19 with 38 correct.
For tests like WISC, all of the components and questions should availble and the only stopping point is based on them getting so many questions wrong in a row.
