There are many situations where it would likely not work Redrobes.

If someone drew their map as a pencil drawing and the accompanying shading is done as cross hatching, then they really do need to do their own shading.
The shading, if one intends to include it, is actually a very individualistic part of someone's map.
To leave off the shading, can be a bit like being asked to do just half a map.

Not to mention, there are a lot of very complex shading things that are likely to go on in these maps.