Appears in collection : Balzan Conference on Open Issues in Gravitation

Gravitational wave modeling increasingly relies on the synergy between analytical frameworks and numerical simulations. In this talk, we explore how information from numerical calculations can be used to inform and improve effective-one-body (EOB) models across different regimes. We begin by focusing on the test-mass limit, where linear perturbation theory provides highly accurate waveforms, allowing us, for example, to probe in detail the merger-ringdown transition in the quasi-circular and eccentric scenarios. We then discuss full numerical relativity simulations of binary black holes, focusing in particular on the transition from unbound to bound motion. Finally, we discuss how to optimally place future simulations in the parameter space in order to maximize improvements for EOB model.