I have experimented with 10, 15, and 20-minute speed geoguessr, and am leaning toward 10 at this point. There gets to be some strategy involved - if you think you can get one answer 6000-point close, it is worth shorting all four of the others to get it.
I still get burned on Australia vs. South Africa, and sometimes American Southwest, because the distance away is so great. In contrast, I have guessed a Taiwan, a South Korea, and a coastal China that all turned out to be in Southern Japan, but still got decent points.
The North Central states really do look like Scandinavia. I miss those sometimes as well. Mexico vs Brazil is also a problem - likely because I cannot quickly differentiate between Portuguese and Spanish. But Brazil is a problem anyway. It's bigger than I realised, and there are often three locations with the same name.
So that's what I've learned, I guess.