Students are always very worried about assignments. If you don’t hand them in to UNISA you cannot write the final exam and thus pass the module. And the assignment count towards your final mark, so they can make a big difference to whether you pass or fail the term.
Also, students are working alone. So they have no one to check with that they are on the right track. So they have NO idea whether or not you will pass the assignment, and have no reference point until they get their mark back as to whether they are understanding the course work at all. And after the assignment is too late – you would have already have received a poor mark, and it is hard to come back from this knock to both your confidence and your final mark.