There are artists out there who have the talent and skill to model every thing from external reference images and don't use image planes.
As a rule though, always use them. Never try it alone
Chris (formerly R@nSiD)
When the power of love overcomes the love of power the world will truely know peace - Jimmy Hendrix
Winner SM VFX Challenge 1
3rd Place SM SteamPunk Challenge (May 2007)