Differential sensitivity as a function of energy for a representative zenith angle of 20◦. An energy spectrum of E⁻², 50h of observation time, a detection significance of 5σ, more than ten gamma events, and five energy bins per decade are considered. The top panel shows the absolute value for the reference monoscopic (full gray line with circles) and stereoscopic (full orange line with triangles) configuration of Unbehaun et al. (2025) and Holler et al. (2016) (both with 1D W-statistics and adapted to 3D Cash statistics) together with the combined Event types (full purple line with stars). The bottom panel shows the relative improvement of Event types with relation to the reference sensitivities. The increase in observation time that would lead to an equivalent sensitivity gain is shown by horizontal dotted lines up to 8 TeV. The region above this energy (noted with a gray zone) is dominated by the requirement of more than ten gamma events.