>>12132922He's right. About 2/3rd of Hoenn is land and you can walk from Goldenrod to Saffron (without the train of course) in a matter of about 15 minutes. Hoenn seemed to take much longer to get anywhere, but I never timed it.
Also, the portion of Japan the Kanto region is in probably smaller in real life than the island Hoenn is based on. Which means Hoenn should be MUCH larger than it is.