“If you are have plenty of time, you are far more likely to end up running late”
On a Wednesday I go home from work, have dinner, and have to be out the door again by 6.20pm, and it seems that the earlier I get home, the more time I think I have, so the slower I take things, and so the more likely I am to end up being late!
ineke.co.uk 
Anything to add...?