PMP exam is for professionals, which means almost everyone taking PMP is already a professional with 8 hours job commitment. That is the main reason, PMP exam prep takes longer. If you can devote 2 weeks at a stretch then you can come very close to giving real PMP exam.

You will have to work with constraints and prepare as much as possible with your daily routine.

There are many folks who take 1 to 2 years to prepare for PMP exam due to other commitments and inability to complete the readings in one go.

Your problem is shortage of time, either its process groups or knowledge areas, ultimately you should know how everything maps to each other.

The study approach differs by each person's level.

Generally it is a good practice to read PMBok or any other similar book full couple of times to get an overall view.

PMP exam neither structured based on process group wise nor knowledge area wise.
The question come randomly.

The usual way to prepare the PMP exam is to study each knowledge area in isolation. This is the organization of every prep book that I know about.

This may be useful in your situation, because a single PMBoK knowledge area can be studied in a reasonable amount of time.

Here you can find an example of PMP study plan:
PMP exam study plan

with a reasoned effort estimate, based upon direct experience.

Regards

Hi

In my opinion, study by KA is an efficient method.as in PMBOK. Understanding of PG is basic requirement. So once you know the PG well, it's better to study by KA as it will be easier for you to relate the processes from KA with PG and your understanding of subject will be reinforced.

I also suggest, not to look at PMP exam through structure of PG and KA. It's the understanding that matters.

You may refer to my study plan at my blog below. All the very best !

http://sachinvehale.blogspot.in/2014/01/lessons-learned.html