Relation between the integration time (t_obs) and the integrated signal-to-noise ratio (S/Nt) for the redshift range 3.5 ≤ z ≤ 5 for single-dish observations. Different colors represent different survey areas, Ω_surv, while the dotted black line shows a reference integration time of 1 year, and the dashed back lack line shows a reference S/Nt of 1. Each panel corresponds to a unique survey.