My 7 days maybe eqivalent to your 30 days. So there is no real need of arguing over 1 week or 1 month. It depends how deep you go into the subject. If you just go for the important topics then it shoud not be more than 2 weeks. But if you want to study it thoroughly (and belive me you need to, if you are not among who just want to pass the subject) it may take between 22-30 days depending on how many books you are following, whether you are making any notes of it or memorizing imp. dates etc.