  The Blandford-Znajek (BZ) mechanism in stellar-mass black hole (BH)
hyperaccretion systems is generally considered to power gamma-ray bursts
(GRBs). Based on observational GRB data, we use the BZ mechanism driven by the
BH hyperaccretion disc to investigate the evolution of the BH mass and spin
after the jets break out from the progenitors. We find that the BH growths are
almost independent of initial BH masses. Meanwhile, the BH growths will be more
efficient with smaller initial spin parameters. We conclude that (i) the BZ
mechanism is efficient for triggering BH growths for only 1 of 206 typical
long-duration GRBs; (ii) the mean BH mass growths of ultra-long GRBs are
marginal for all 7 samples collected; (iii) for the short-duration GRBs, the
results that BHs show minimal growths is consistent with the mass supply
limitation in the scenario of compact object mergers.
