the rule in WB is 3, i believe, as well, that 5-6 textures in a few chunks wont be a problem for most players, but it is not necessary ! A map builder with a minimum of skill will almost allways be able to replace at least two of five textures with splats.
Yeah i know, it is much easier just to paint it all on.......
But textures puts a lot of strain on your GPU, try making a chunk with 10-12 textures and see what happens