The review of experimental and analytical investigations on 3D-analysis of spatial anisotropy and relevant search of extreme values for induced (electro-, piezo- or acousto-) optic effects in anisotropic materials is carried out. On this base it is the important fundamental conclusion: the directions of the electric field, uniaxial pressure and the polarization of light or acoustic wave that provide the greatest values of such induced optical effects for investigated materials generally do not coincide with main axes of crystallografic coordinate system. In addition, the application of anisotropic materials at maximum induced optical effects will enable to reveal the large hidden reserves to enhance their perfomance, that have yet never been used and often even quantitatively not been studied.