MAX TEXTURE ATLAS SIZE DEFINITION (DOPEYDAVE)

I was wondering the same thing this website defines its well say 20 building in the map ahve the same walls a texture file is a big file with tons of different pics in it basically so it loads one big picture and uses all the parts of it for dif buildings/tiles in the game

http://www.gamasutra.com/blogs/DavidRosen/20100326/4777/Using_Texture_Atlases.php

Follownig from above adress.

So a texture is an image that is wrapped around a 3D model to add apparent detail -- but what's a texture atlas? A texture atlas is an image that contains multiple textures. For example, below you can see a character texture on the left, and a texture atlas on the right (with four character textures).