Thats correct. Whether a brick texture or a fabric texture, it needs to be tileable. There are plenty of tutorials available on the net to explain the process on how to create a tileable texture.
If you are resizing the image (and not resampling), this is where you need to decide the pixel count - here.
If you re-size the image (in photoshop) then that would be the case. However, if VW reduces (in size, not pixel count) and tiles the texture image in a render, say a rendered wall, then your pixel count could be too dense, hence increasing render time and file size. Unless VW Resamples the texture somewhere in the render process.
One still needs to be aware of what the target pixel count should be when creating the texture.