How many Investigation Workbook pages should students produce?

Some examiners have recently expressed concern that some teachers are allowing their students to create a relatively small small number of investigation pages. In one case an HLA student completed only about 50 pages over the two years and chose half of this number to be assessed in the final examination. Perhaps predictably, this student did not do very well. As is so often the case, its a quality vs. quantity issue. Obviously it serves very little purpose  if students just  produce a ...