Heya!
It's more a quality > quality approach when it comes to 15 markers. Though for the length, it kind of differs for Historical Society and Personality Study. For the society, there are two/three other questions whilst for the personality study, there's only one other question. But 15 markers should be approached like a mini essay- so the better the integration of sources and your explanation, the better your marks
Historical society:
15 marker should take around ~20-25 minutes so about 3-5 pages should suffice (this depends on how small/big your handwriting is!) Around three body paragraphs should be fine.
Personality study
The 15 marker should take around ~20-30 minutes so 3-4 pages should be fine (again, this depends on how small/big your handwriting is). This 15 marker mini essay should be longer than of the 15 marker in the historical society section as you are only given 2 questions in the personality section rather than 3/4 questions in the societies section.
If anyone else has any insight, feel free
The marks for each question should determine how long you should write for and for how much you need to write. Hope this helps