When are FrameworkElements rerendered when the RenderTransform has been changed?

When are FrameworkElements rerendered when the RenderTransform has been
changed?

Let's assume I set the RenderTransform value like this:
(RenderTransform as TranslateTransform).X = 10;
(RenderTransform as TranslateTransform).Y = -10;
instead of doing:
RenderTransform = new TranslateTransform(10, -10);
Does this have any effect on the rendering process? Or does the rendering
process even occurr twice (once for each property)?