So this is the story.
Basically if your work permit is going to expire and if you do not have any supporting document in hand to get a work permit, your workpermit application will be rejected by CIC. After recieve your rejection letter/email you need to stop working and need to restore your status. But during the process you are in implied status. That's mean you can work and have some money save for your next application and meantime you can try to find LIMA or another employer who can provide a LIMA (or get PNP certificate and supportive letter).
If you receive one of these supportive letter before they process your application, you can submit it to CIC, and they will approve your application.
If you apply online, it is fast and decision will be made so fast.
If you use paper application, it will take time to process and you have time to do your other work as I mentioned earlier. So basically we use paper application to late the process, and get more time to prepare for next step.