Ratio of the observation delay T_delay and T₉₀ vs. T_delay for the GRBs listed in Table A.1. GRBs with and without redshift are denoted by red and blue markers, respectively. The dashed horizontal line denotes when the ratio is equal to one, meaning that for GRBs with a ratio lower than one, observations started on a timescale comparable to the duration of the prompt emission. For the sample under consideration, the GRBs fulfilling these conditions are GRB131030A, GRB141026A, GRB150428B, GRB170728B, and GRB180720C. The only GRB from this sample that was significantly detected at TeV energies, namely GRB 190114C, is marked with an empty circle.