Hi I have a problem when texture painting on a huge plane.
Whenever I zoom or pan my view (even just pan without zooming) and paint on a location I painted before, the texture gets an offset and of course does not fit anymore to the rest I painted.
You can use stencil for the brush mapping. This gives you a semi-transparent overlay of the texture that you can position before painting.
You can use RMB to move the texture ⎈ Ctrl RMB to rotate it and ⇧ Shift RMB to scale it