After all if you get pedestrian crossings, you need to see them an identify them from a much further distance than you normally do, this will give you chance to either fully guide the pupil or at very leat prompt them for info. You need to be able to spot the crossing, identify what type of crossing it is, (controlled/uncontrolled), pelican/puffin/toucan, and then be able to say what if any action needs to be taken an approach. But it really is scary the amount of trainee driving instructors who are unable to do this, and as a result you know they are not doing this with there pupils.
Also of importance is to at least moderately get to know the general area where your part 3 test is being held, if you don't know an area, you face a real uphill battle to be able to fully guide and teach effectively, as you can be sure that you will put extra effort into looking ahead, rather than focusing on the pupil. This results many time in those on driving instructor training courses not even being able to tell me the speed limit of the road we are on, due simply to the fact they are unsure of the area and are having to deal with a hundred things at once.