The growing demand for lightweight yet robust materials across various fields has driven the development of ultralight architected materials with engineered microstructures and tailored properties. Among these, truss metamaterials – composed of beam networks arranged in a repeating periodic lattice at the micro and nano scales – have attracted significant interest. While the mechanical behavior of these materials has been explored through numerous modeling studies, the selection of modeling assumptions often lacks consistency and clear rationale, particularly in relation to specific mechanical regimes of interest. For instance, traditional beam theories – such as Euler-Bernoulli, Timoshenko and Kirchhoff-Love – have been extensively studied and compared at the single-beam level. However, systematic assessments of their applicability to lattice structures, particularly in relation to the modelling of beam intersections and finite-sized joints, remain limited. Addressing this gap is critical, as the characteristic dimensions and microstructural effects of such metamaterials are known to challenge conventional assumptions applicable for bulk homogeneous materials. As a first step toward defining suitable modelling approaches for different material properties, geometrical configurations, and loading conditions, this study systematically assesses the importance of joint-modelling assumptions in truss metamaterials. The central objective is to determine the level of joint fidelity required to accurately simulate lattice structures undergoing nonlinear deformation. Different joint representations and beam formulations are evaluated for representative stretching- and bending-dominated architectures. Their influence is quantified in terms of effective stiffness, energy distribution, stress localization, and post-buckling response. These analyses provide valuable insights into how modeling choices influence simulated responses. Based on these insights, practical guidelines can be established for accurate and efficient computational modeling, enabling a streamlined design process for lightweight and impact-resistant truss metamaterials.