...
Providing a RUNLIMIT let's the scheduler know what the required time window for your job is. Without an explicit RUNLIMIT, the scheduler can only assume your job will run as long as the default RUNLIMIT for the queue, this default is often far greater than many jobs need. For example, the xlong queue currently has a RUNLIMIT default of 72 hours but queue statistics show the runtime average for jobs in this queue is currently ~2 hours.
...