This makes me question where you found the approval timelines for all Canadian PRs. Anecdotal observations are not evidence, and you need look no further than this thread to find counterexamples.

But to answer your original question, it depends. It depends on your own background and whether there's anything in it they need to look into further. It also depends on CBSA *and* CBP systems, and where you end up in the queues for both. Your randomly assigned caseworker might be neglecting your file. And since they won't disclose any of this information, there's no way for an outsider to tell.

If it makes you feel any better, I applied for NEXUS renewal as a US LPR and it took so many months that I became a US citizen in the interim. LPR applicants do not get preferential treatment to citizens, either in the US or Canada.