As mentioned, the adiabatic equation assumes no heat is dissipated from the cable during a fault. While putting the calculation on the safe side, in some situations, particularly for longer fault duration there is the potential to be able to get away with a smaller cross section. In these instances, it is possible to do a more accurate calculation.
Considering non-adiabatic effects is more complex. Unless there is some driver, using the adiabatic equations is just easier. Software is available to consider non adiabatic effects, however, there is a cost, time and complexity associated with this.
The IEC also publish a standard which deals with non-adiabatic equations:
The method adopted by IEC 60949 is to use the adiabatic equation and apply a factor to cater for the non-adiabatic effects:
I=ε I AD
where I - permissible short circuit current, A (or kA)
IAD - adiabatic calculated permissible short circuit current, A (or kA)
ε - factor to allow for heat dissipation from cable
The bulk of the IEC 60949 standard is concerned with the calculation of ε.