I disagree. Routes are path of least resistance. Your default route is nearly always going to be faster than adding another hop to the mix. There may be one offs, but they would be extremely few and far between.
So it doesn’t depend on the route your ISP takes, the route your VPN takes, and a few other factors? Please, then, enlighten me.
Experimentally this is not true at all, a very common situation is for people to set up VPNs to reduce ping, because ISPs use least dollar cost not quickest routing. I’ve even seen one guy whose ISP went from Switzerland to UK through NY 
I’ve even seen one guy whose ISP went from Switzerland to UK through N
“Least resistance”…nice subjective abstraction