As Slasher says, adjust your 'extra' fuel for the weather.
It is often forgotten that the 'Div' fuel on your PLOG is from DA at destination. IF you make a sensible EARLY decision, either before TOD or soon after, you will have LOADS of fuel to reach even a far-away DIV and land with RESERVE, making INTRUDER'S logic the only sensible one if both DEST and planned DIV are rubbish.