I think the reason it works is because the longer you put something off for, the higher the chances that the bad timing coincidence will occur. For an example, the restaurant. If you wait 5 minute maybe there is a 5% chance of them bringing the food out within a minute of you reaching for something else. Now if 20 minutes go by your chances might increase to say 65% chance. Now your never going to have it happen all the time but if you raise your odds to 65% by waiting a long time for everything it would seem like it happens all the time.

Anyway to your question, I think the only reason it works is because your so slow and deciding what you want to do. If you decide to hurry it along without delaying far more than needed, you might actually have time to get everything done before they show up heh.