I'm a bit of an after effects newbie, so I hope you can bear with me!
I'm trying to gradually reveal a more complicated vector shape object, for argument sake let's say a figure of 8. So I want it to look like it's being drawn on and following the curves of the figure of 8. Is the best way, or only way to do this write-on tool. It seems that the tool is fairly limited with how big the brush can go, and also controlling it so that the brush doesn't overlap into other sections of the shape as it's writing on.
Try playing with the Trim Paths effect. You can add it by clicking the arrow next to "Add:" on your Shape Layer contents. Using that, you can keyframe your start and end points to be 0% complete to 100% complete and it will "draw" your shape. Is this what you are trying to accomplish?