Nice to know, Gator48, but that's not quite what we're referring to.
We're talking about how the monitor continues to display a reading from memory for up to an hour while in reality the monitor has lost the sensor's signal.
You may be getting a signal from 100 feet away, but it is just as likely your monitor is displaying a reading from its memory while the signal from the sensor has actually been lost.
Place your monitor and sensor a mile apart and see how long it takes your monitor to alert you that a signal has been lost.
I drove into town, leaving my sensors at home on our camper and still had phantom readings on my monitor for nearly an hour.