I find it odd that the greater the complexity governing arrival, the closer the actual time of arrival tends to be to the planned time. For example:
1. Send a spacecraft from Earth to Mars (~10 months travel time, Spaceship) and it touches down to the second;
2. Fly from San Jose to Seattle (2 hours, Jet) and the flight arrives within 5 minutes of scheduled arrival;
3. Ask for a Pacific Gas and Electric employee to visit your house (5 minutes, car) and the best they can do is to provide a four hour window.....
Now, I'm sure we can all think of many exceptions to this rule. But it still pisses me off that PG&E scheduling is so crap. Get a day planner!
(4. If your significant other is asked to do a job and has zero distance to travel and zero complexity associated with getting to the site of the intended work (e.g. bathroom to fix a leaky faucet), the work will never get done).