I think it's likely that higher intelligence could evolve more often were it not a "first past the post" race where whichever species gets there first prevents

I think it's likely that higher intelligence could evolve more often were it not a "first past the post" race where whichever species gets there first prevents the others from doing so by squeezing them out with regard to the necessary natural resources. Thus, I'm inclined to think that if there are many planets with the required ingredients for life, there could likewise be many examples where intelligent life has arisen, but like on Earth, limited to one advanced species per planet.