Yes.
The purpose of an exam is to rank those who do it from first to last. A question that no one can do is not worth asking because it simply reduces the number of marks available for separating students into a ranking order. A question that everyone can do is similarly useless in an assessment sense, though such a question at the start to get everyone "settled" (so to speak) may be included.
An HSC has to rank every student in the state (a population) whereas a school assessment needs to rank only a sample of that population (being the students at that school). Thus, a school assessment should be tailored to the characteristics of the sample. If a school has 100 students sitting an exam and 40 of them will score an ATAR of 99+, 70 of them will be 95+, and 95 of them will be 90+ (say), then the sample's average academic performance is much higher than that of the population. Setting an "average" exam could well mean that there are 70 students to rank who scored 75%+, making some of them difficult to distinguish from others. If the average is reduced to 60% (say) by asking harder questions, the spread of results is likely greater and thus the ranking order easier to distinguish.
For essay-based assessments, the same effect can be achieved by setting marking criteria that are more severe than would be used if the same question were asked in an HSC exam.
In short, the more able you are in a subject at your school, the more important that it is to seek out challenging material, and most especially if you are atypical of the sample and so have assessments that are easy when compared against your capability.