They are instead being asked what is there, and the teacher's efforts are directed to seeing that they get it, rather than to seeing whether they know it. So in choosing how to gap a transcript there may be various criteria for taking out one segment rather than another, but the main constraint is that any language excised should be well within the structural and lexical grasp of the target class. On paper the text above perhaps looks as if its language could be accessible to a range of levels, from mid-intermediate to advanced, and normally this would be true, because one of the huge advantages of SAD is how flexibly most materials for it can be used. That is, using the capability of word processors to store many formats of the same text, most SAD transcripts can be varied in difficulty simply by keeping different versions with different gaps. The sole reason that this particular transcript is exclusively an exercise for advanced students, is simply the speed at which Heather speaks.
Intermediate students find it hard even to keep their place in the transcript.
One criterion for the teacher's decision as to where to put gaps in the transcript is therefore the level of difficulty. After that, there can be various possibilities. It is certainly arguable that the various analytical processes which go on when students are doing a demanding SAD exercise can be so valuable in themselves that creating an additional objective by using the exercise mainly to practise a particular form is over-egging the pudding. But this would be to miss the point of SAD by focusing students too much on bottom-up processing. In one sense, doing SAD is doing pronunciation.