You do not need to be "at the right place, at the right time". As mentioned on here, you can get pings from 20 minutes away. (That is a pretty good radius). When Uber finds the closest driver, it does not take into account, if you have to go 3 miles to the next exit to turn around.
i.e. I have been cruising on 59 North and get a ping from the Hilton Americas. My closest u-turn is outside downtown. Surely, I am not the only driver in Downtown.
Therefore, if you are sitting at your house, the Uber algorithm is going to calculate your distance compared to that of another driver. It's going to draw the route straight through houses, buildings, etc. (as if you can fly over those buildings to get to the rider). It is not going to calculate your exact route (using roads), nor that of the other driver that may get the ping.