The model sheet for my timepiece was fairly easy and comparatively quick to make, because I only need three different angles to make the design workable, those being front, side and 3/4 views. If I was doing a model sheet for a building, or asymmetric object, then I would need to do an additional view, and if I were doing this for a character, then it would be useful to get top-down and bottom-up so that the character model can be created accurately.