What is happening here is the following.
You are using shrinkwrap with the "project" option.
In this case, the mesh is projected along its face's normals (the arrows in the image below)
Even if two points are close (like in -1-), their projection following the arrows (in -2-), makes a larger segment which is cut by Spiderman's face.
To obtain a better result (with less vertices), you should roughly follow the face curvature so that the projection can be done appropriately.
Here is an example:
