When is it vital to Use Normal maps?

Normal Maps can be used in all kinds od scenarios but I would say that is vital to use Normal Maps when the geometry of the object exceeds the maximum allowed number of polygons for that particular object.

Generally it is used in games, but lately I have been using normal maps in all kind of scenes in3d rendering.

Excellent way to preserve fine details wthout the need for polygons to define the detailed surface.

best way to optimize speed of game is to use normal maps with non complex shaped objects(low poly shapes),  that can be display as walls, doors, etc.

Great answer... except it can be used with every kind of model even characters