  We present an alternative approach to deriving second-order non-conformal
hydrodynamics from the relativistic Boltzmann equation. We demonstrate how
constitutive relations for shear and bulk stresses can be transformed into
dynamical evolution equations, resulting in Israel-Stewart-like (ISL)
hydrodynamics. To understand the far-from-equilibrium applicability of such ISL
theories, we investigate the one-dimensional boost-invariant Boltzmann equation
using special moments of the distribution function for a system with finite
particle mass. Our analysis reveals that the mathematical structure of the ISL
equations is akin to that of moment equations, enabling them to approximately
replicate even the collisionless dynamics. We conclude that this particular
feature is important in extending the applicability of ISL theories beyond the
hydrodynamic regime.
