  Using 2D smoothed particle hydrodynamics, we investigate the distribution of
wait times between strong shocks in a turbulent, self-gravitating accretion
disc. We show the resulting distributions do not depend strongly on the cooling
time or resolution of the disc and that they are consistent with the
predictions of earlier work (Young & Clarke 2015; Cossins et al. 2009, 2010).
We use the distribution of wait times between shocks to estimate the likelihood
of stochastic fragmentation by gradual contraction of shear-resistant clumps on
the cooling time scale. We conclude that the stochastic fragmentation mechanism
(Paardekooper 2012) cannot change the radius at which fragmentation is possible
by more than ~20%, restricting direct gravitational collapse as a mechanism for
giant planet formation to the outer regions of protoplanetary discs.
