Distributions of number of GRBs per number of peaks for different catalogues: CGRO/BATSE (top left), Swift/BAT (top right), BeppoSAX/GRBM (bottom left), and Insight-HXMT (bottom right). Observed data and expected counts are shown in orange and blue, respectively. All histograms have been grouped so as to ensure a minimum number of counts per bin. Dashed lines show the best mixture model of two exponentials that fit each distribution. Grey models are the result of a random sampling of the posterior distribution of the parameters as determined via MCMC.