Thanks for the reply !Yes, they do verification in some cases. I got a call from SGVO regarding my marriage and the accompanying family members. So it was kinda another BGC, but eventually got our COPR and visa stamped.
As for your other question why some get it in 3 days, others 3 weeks. It is also the same as the EE processing, some get the PPR in 3 weeks, others in 3 months or 3 years No one really knows how they process our applications.