  We investigate the typicality of the growth behavior of the
out-of-time-ordered commutator (OTOC) in the many-body localized (MBL) quantum
spin chains across random disorder realizations. In the MBL phase of the
Heisenberg XXZ chain, we find that the estimate of the OTOC fluctuates
significantly with the disorder realizations at the intermediate times of the
main growth. Despite the consequent failure of the disorder average in the MBL
phase, we argue that the characteristic behavior of the OTOC growth can still
be identified by going through individual disorder realizations. We find that a
power-law-type growth behavior appears typically after a disorder-dependent
relaxation period, which is very close to the $t^2$ form derived in the
effective Hamiltonian of a fully MBL system. The characteristic growth behavior
observed at an individual disorder realization is robust in our tests with
various state preparations and also verified in another MBL system of the
random-transverse-field quantum Ising chain in a uniform longitudinal field.
