*2.1. BATSE*

The BATSE 64 ms-binned light curves were stored as ascii files on the BATSE Public Data Archive (https://heasarc.gsfc.nasa.gov/FTP/compton/data/batse/trigger/, accessed on 17 February 2021). There were 2704 bursts in the final BATSE catalogue from 21 April 1991 to 17 August 2000, and 1956 light curves at 64 ms resolution were available. Background subtraction was applied via polynomial fits to the 64 ms light curves pre- and post-burst. The BATSE 4 ms-binned light curves were generated using the TTE files for individual bursts in the BATSE Public Data Archive, which stores 1732 TTE files, 1721 of which have successful background subtraction. The count rate was divided by the number of triggered detectors to obtain light curves measured in counts s−<sup>1</sup> det−<sup>1</sup> . The resulting light curves were stored in the four standard BATSE bands (20–50 keV, 50–100 keV, 100–300 keV and >300 keV).

#### *2.2. Swift/BAT*

The *Swift*/BAT Gamma-Ray Burst Catalogue (https://swift.gsfc.nasa.gov/results/ batgrbcat/, accessed on 29 January 2021) hosts ascii files containing the 64 ms- and 4 msbinned background-subtracted light curves. There were 1388 GRBs detected between 17 December 2004 and 28 August 2020 in this catalogue, which was extended from the Third *Swift* BAT Catalogue [80]. 1273 light curve files were available at 4 ms resolution, containing four background-subtracted light curves, corresponding to four bands (15–25 keV, 25–50 keV, 50–100 keV and 100–350 keV) in units of counts s−<sup>1</sup> det−<sup>1</sup> . Twenty-two bursts with no documented duration (T90) were removed from the sample. At 64 ms resolution, light curves were available for the same set of bursts, with three additional GRBs added to the sample.
