Oh I'm not a newbie to all this by any means in that we've been around the block more than a few times in regards to updates and their delays. As for patches, sure they may come from the manufactures yet carriers (in this case Telus) still has to approve, and possibly put their spin on things, before an actual release to the public. I'm sure you are aware of PTCRB Certification requirements for North America. Essentially once they've pass this certification they are up for release.
Anyway all's good now as our P20 received it's March Patch on the 29th approximately 10 days after our Pro did.