So islands belong to the nearest large landmass? I guess you could do that, but then where's the threshold? Obviously, Africeurasia has to be a continent if you want there to be any continents, and America probably is too, but then is Australia a continent that includes NZ and some other islands, or is it part of Africeurasia? How about Greenland? Are the Diomede Islands really on two different continents? Indonesia would be too, if you count Australia as a continent.

I'll give you that that's geologically consistent while being culturally independent, but it's pretty inconvenient.