World Position Offset (vertex position)

Hi everybody. I have a problem with world position offset. The purpose was to move every part of a mesh independently. I created a mask whith checker pattern node, but it looks like not every vertex is in the mask. What am i doing wrong ? Every uv shell is 1\3 square.
P.S. sorry for bad english. I attach picture that shows the process

Try to substract AbsoleteWorldPosition

I decided to draw mask in another way. I drew five lines, and multiplied them. Every square of a mask perfectly covers each uv shell. But when i when try to move part of a mesh, only one is moving. Then i made a little padding on my uv’s, and it works perfectly. I don’t understand why sometimes mask works and sometimes not.3af9d7db4173999e60a8c83e94323e56ee556de5.jpeg

It is would be cheaper solution if you simply paint those quads vertices in different vertex colors and use this colors as masks.
Especially if you need 4 of them - black, red, green and blue.