Hope you checked carefully the latest changes about PCC requirement posted at IRCC websiteNot necessarily in a row, it's in total. So if you visit a country frequently and the total number of days you've spent there since your 18th birthday is 180 or more (6 months), you may need a PCC from that country.
My brother, who is now a PR (got CoPR 2 weeks ago), had IRCC request an FBI police check even though he has never lived in the US after his 18th birthday, but he travels there frequently and his total number of days was over 180. Even though some pages in the CIC website say "6 months in a row", in some other places it says anywhere you've spent 6 months or more in total, wether living or traveling. So just in case I'd get all PCC's that could fall into that.
You are right as per old requirements, but that rule doesn't exist anymore and your brother's application has been reviewed with that old regulation
PS: Always IRCC officer may request a PCC if he/she feels that's necessary, it's officer's discretion without a question
regards