The ability of organisms to spontaneously generate order relies on the intricate interplay of mechanical and biochemical signals. If the general consensus is that chemical signaling governs the behavior of cells, an increasing amount of evidence points towards the impact of mechanical factors into differentiation, proliferation, motility and cancer progression. In this context, several studies recently highlighted the existence of long-range mechanical excitations (i.e. waves) at the supra-cellular level. In this review, we discuss all recent observations of mechanical oscillations on in vitro monolay-ers on a planar geometry, and their potential role for the patterning of cellular behavior at large scales. We focus on the importance of externally imposed confinement on the appearance of different phenotypes, namely traveling and standing waves, and how these mechanical stimuli might have a different potential for future research. We tackle the debate of whether oscillations are innate to the cell or only dependent on the boundary conditions, and propose a framework to reconcile these two points of view. We conclude with an outlook on the future of this field, and the directions to be explored in order to give mechanical oscillations a biological role.