large 'open world' map = giant paintbrush?

Why does terrain size affect brush size when painting textures?

Answer: the paint brush tool is based on the terrain grid size, so your not actually making the map 'bigger' you're streching what was already there. you can adjust the grid size by using control texture resolution, the bigger the resolution the smaller the paint brush the higher the memory required, i don't know what the others do or anything :P

are smaller maps encouraged based on the paint brush size? is it possible to there for attach another terrain to a pre existing terrain to keep a small paint brush? or should the 'open world' be segmented to load up? :D

i looked here n there but :D some of these responses are from years ago :D thanks for any help :)