The paper shows the pattern of change in the deformation dependences (DD) of integrated intensity of dynamical diffraction (IIDD) with crystal thickness and with variation of other diffraction conditions by means of the Chukhovskii—Petrashen theory for the DD of IIDD in defect-free crystals. Relying on this and numerous other experiments with real defective crystals as well as the results of total integrated intensity of dynamical diffraction (TIIDD) in crystals with defects without bend, an analytical model of the DD of TIIDD in crystals with defects is developed, which is feasible for the diagnostics of structural defects in crystals. The heuristic model constructed for the DD of TIIDD in crystals with defects considers the DD of reflectivity and absorptive power of crystal, whose contribution is determined by model parameters ($\alpha$, $\beta$, $\gamma$, ...) for both Bragg and diffuse components of TIIDD. As found, the sufficiently accurate DD description with fixed parameters and single description expressions is only achieved in certain narrow ranges of deformation radii. However, these parameters are selectively dependent on each set of parameters of diffraction conditions (wavelengths, crystal thicknesses, reflection indexes, diffraction geometries, etc.). As shown, the construction of the heuristic model of the DD of TIIDD in crystals with defects as a diagnostic method has only become possible because we were able to factorize the effect of microdefects and deformation parameter on coherent and diffuse components of TIIDD, separately; but it is important to save non-factorization of their effect on total IIDD.