One of the most interesting recent advances in holography were developments of numerical techniques for anti-de Sitter gravity. I will discuss lessons that we learnt from applying this technology in the context of heavy ion collisions and the physics of strongly coupled quark gluon plasma. More specifically, I will discuss recent distinction made between thermalization and applicability of hydrodynamics, the so-called ``hydrodynamization", and I will show that hydrodynamic gradient expansion is an asymptotic series. I will conclude by discussing a holographic toy-model of a heavy ion collision exhibiting a crossover between full stopping and transparency scenario.