I recently attempted to edit the proposed contours on a site model + ended up making a complete mess of the terrain in the area in question. After exiting the edit mode, all looked fine in Top/Plan but when I changed to a 3D view I could see that in between my contours the terrain had lots of dips/holes/sharp edges + general irregularities. When I reduce the interval between the contours in the settings to display more lines, I could see that the intermediate contours were very twisted + messy +