You can set the rapid speed of the machine and the pierce time. The cutting time assumes the machine does not have to slow down for corners. I am a little surprised it makes that much difference though.
The main problem lies with most plasma machines as they cannot maintain a constant feedrate due to slow accelleration. With a very artsy detailed cut the machine spends a great deal of time at 30-50% of specified feedrates due to CV and settings. Therefor a larger margin of error on completion times.
I have noticed the slowdowns in cut rules don’t seem to be accounted for in the job report, but someone the other day pointed out to me in simulation mode the seconds timer that gives accurate run time, speeded up to 5000% or so it works great.