pretty sure its 2 weeks... but yeah i dont think they HAVE to, its just the way it is. if u get more u must be really lucky, coz u gotta get lotsa assessments done in a relatively short space of time, so unless its an extended research project that u could reasonably expect to take more than a fortnight, then 2 weeks is the norm 2 make sure it all gets done. u should have a schedule saying when they're due anyway, so u can prepare a little before the task is set officially.