To be honest the answer to your question will come from one of two groups. The first say that the on board computer will monitor your driving style and will be quite happy for the oil to be left in the engine for 15 / 20,000 miles.
The secound group (of which I am one) will change the oil every 7 / 8,000 miles as we believe new clean oil is good for the engine and the turbo etc.
The choice is yours. You might like to read 'Honest John's' views on oil changes - he agrees on regular changes of oil.