It very much depends on how many files your Visa Office is dealing with. Based on what I have seen in the tracker, and been told by IRCC, the average is around 2 months unless CSIS wants to do a more comprehensive investigation. As an example, here is my experience with the London VO since the time the medical passed, and security checks began.
Pass Medical: 23 Jul 2022
Ghost Updates: 2 Aug 2022
Letter Request (Dependent Schedule A): 4 Aug 2022
Ghost Update: 5 Aug 2022
Uploaded Schedule A: 7 Aug 2022
Confirmed CSIS working on Schedule A: 7 Aug 2022
Ghost Update: 8 Aug 2022
Ghost Update: 15 Aug 2022
Ghost Update: 16 Aug 2022
Ghost Update: 18 Aug 2022
Ghost Update: 19 Aug 2022
Ghost Update: 25 Aug 2022
Ghost Update: 26 Aug 2022
Ghost Update: 30 Aug 2022
Ghost Update: 31 Aug 2022
Ghost Update: 1 Sept 2022
Ghost Update: 2 Sept 2022
Ghost Update: 5 Sept 2022
Ghost Update: 6 Sept 2022
Ghost Update: 7 Sept 2022
Ghost Update: 8 Sept 2022
Ghost Update: 9 Sept 2022
Ghost Update: 12 Sept 2022
Ghost Update: 13 Sept 2022
Ghost Update: 15 Sept 2022
Ghost Update: 16 Sept 2022
Phoned In: 16 Sept 2022 - Confirmed Only CSIS Remaining since 7 Aug 2022.
Ghost Update: 21 Sept 2022
Ghost Update: 22 Sept 2022
Ghost Update: 23 Sept 2022
So based on what IRCC has told me, all of these Ghost updates are considered a normal part of the background check. Typically I see this many ghost updates within the last 4 weeks before Passport Request or Virtual Landing email. I hope this helps...