Most application are processed within 6 months. Now let me unequivocally an unambiguously state:
The 6 months processing time starts from the day when your R10 is passed.
The 6 months processing time does not start from the day of the AoR. The R10 is usually passed within the first 20-45 days. R10 is also called the completeness check. As per Regulation 10 of the Immigration and Refugee Protection Act (IRPA), it is an absolute liability on the applicant to ensure that his application is complete, i.e. all the supporting documents are submitted. If anything is missing the application will be rejected. This is why there is no point requesting GCMS notes within the first 45 days, as even if any document is missing you cannot do much.
By the time R10 is complete, so is criminality, which is based on your PCCs, and Medicals are also passed.
After this comes the most important stage, ELIGIBILITY, also knows as A11.2. This is where the GCMS notes play a very vital role. The eligibility takes place in 2 stages. First an program assistant or analyst will review an application and then the recommendation is reviewed by an officer who makes a final determination. This stage is also the longest, barring any security or SS. Many times the program does not take into account your work experience, or forgets to review a document, or simply determines that your work ex does not meet the program requirements. As soon as you see these in your notes, you can raise a CSE and send more documents, which will then be review and hopefully you will save your application form getting into procedural fairness.
During the eligibility, you may end up requesting GCMS notes, 2-3 times. After the eligibility is passed, the BGC starts. After the BGC starts, there is nothing much an applicant can do expect wait. However, even after the eligibility is passed, sometimes the BGC never starts. This is when the GCMS notes will do the magic for a few as they force the officer to review the application fo GCMS notes release. If the eligibility is passed, but not updated in the system he will do so and initiate the BGC, and you see a movement in the application.
Similarly, when the BGC is complete, i.e. the CBSA and CSIS have sent in their reports, you application may keep sitting, and when GCMS notes are requested the officer will simply update your application and will put it in queue for PPR release.
This is how in some cases GCMS notes play a vital role.
Requesting GCMS notes is entirely a personal decision. You don't have to request GCMS notes. IF you do not request GCMS notes, then the application will progress at its own pace and you will only see the MyCIC status updates.
The whole criteria of IP1, IP2 etc. is based on MyCIC updates, and to use my words carefully, is nothing more than a waste of time and baloney. An application for PR goes through the following stages:
R10
Medicals
Criminality
Eligibility
Security.
The IP, IP2 is way to predict that if MyCIC status shows a certain update, it would mean that the application has passed a specific stage, which is just speculation and nothing more. Instead of that, an applicant can see the calendar and make assumptions, which is also as foolish as anything else.
Hope this helps and answers your question.
To read more on the stage of an application see:
https://www.getgcms.com/blog/express-entry-application-processed/