Learning how to write an exam, in the year it costs least
For most learners Grade 8 is the first year of high school and the first time they sit formal, timed examinations in every subject on one timetable. The content is rarely the hard part. Budgeting time across a two hour paper, reading a question properly, and knowing when to move on are the skills that separate the marks.
Those skills are learned by doing papers, not by being told about them. A learner who has worked through five real Grade 8 papers walks into November knowing what the thing looks like. A learner who has not is meeting the format and the content at the same time.
Grade 8 is also the cheapest place to get this wrong. Nothing here follows a learner into the Grade 12 final mark, so it is exactly the right year to discover that you always run out of time in the last section.