I've seen someone post a seed where the starting island was super tiny, just a very small meadow and no other biomes. And I've seen a seed where the starting island was massive, with every biome in abundance other than Mistlands....no need to ever sail until you need Mistlands.
RNG and procedural generation is wacky that way.

@Suzaku, here's two seeds that give a meadows-only starting island (found the thread I mentioned):
QhsT2KVdEb
FLOrida