No one can really tell. Depends on the officer on your file tbh... What I have noticed is that it would also depend on the nationality of sponsor and PA...
e.g Both are The same nationality (Sponsor: Filipino PA: Filipino) it's faster than Canadian - Filipino... They deny this but it's pretty obvious...
As I often do, I caution that it's really, really hard and potentially misinformative to draw conclusions esp about nationality and how this affects things - we don't see a represetnative sample, for example.
Even more so for inferences when it comes to minor differences like this - the biggest problem being, we don't see the underlying differences between relationships and documentation. (Let alone trends about misrepresentation, attempted marriage fraud, and other 'risk factors' that change over time).
For example here, it may seem nationality/nationality differences, but it could well be length of marriage, children, age differences or dozens of other thigns that are different that are more likely to be the 'cause.'
And of course, sure, it can just be different officers (one working full time on spousal and another splitting time iwth other responsibilities, for example).
[There are of course some nationalities that clearly take longer - security risk countries among them. No question. But sometimes the inferences about favouritism are way overstated]