I never seen this done before in a running race. One day you will feel really good but you are so intent on just breaking your PB you will never know what you are capable of and then never to reach that height again.
Or to put it more succinctly, gimp.
Whoa, I seem to be getting a lot of abuse lately!
This isn't like a 10km or half marathon race, where I would never ever slow down to just beat a PB. But the scoring for The Trunce series gives you lots of bonus points each time you beat your PB. That's the only reason.
Ok - a little gimpish as it gives you a kick! :-)