Do devices really have a sweet spot?

Opinions vary greatly regarding the state of the economy. Many American households are still in a “hunker-down” mode, trying to save a few dollars wherever they can.
A family might still take a vacation, but it’s somewhere closer to home so that it amounts to either a day trip or is no more than an overnight excursion.
To save a little bit on a household’s transportation budget line item, trips to the grocery store are being consolidated so that single-item excursions are eliminated.
As utility bills creep higher, people are doing what they can to conserve a little here and there. In the Henley household, this has meant closing the heat vent to an unused bedroom. The back door is regularly dead-bolted so that the winter jet stream of cold air isn’t continuously invading. A light in rooms where nobody is present is shut off as is the television when the only one seemingly watching it is a stuffed animal. Anyone washing their hands or doing dishes is vigilant about making sure the faucet is turned off completely.
If not working properly, potentially one of the big money wasters in a home is the toilet. If allowed to continue running, one could find a very expensive water bill arriving at the end of the month.
There have been times when the inner seal of our upstairs toilet has worn, allowing water to continue flowing long after the tank should have filled. A new rubber “flapper” typically takes care of the issue.
Recently I’ve noticed after the toilet’s tank has filled there has been a sound of water continuing to run. It hasn’t bothered me too much because (A) unlike when the rubber seal needs replacing, the amount of water still running is very slight; (B) unlike when the rubber seal needs replacing, this slight flow of water will stop within a minute or so.
I know, I know. A real handy man would break out his low-riding jeans and tools, and tear into the apparatus and keep tweaking until the problem is solved. Unfortunately, I’m not the handiest of men, so I’ve chosen to not touch something that’s still functioning pretty close to normally.
Recently, however, as I exited the bathroom with water still trickling in the toilet bowl, I found myself being scolded by my teen-age daughter, Anna.
After explaining my philosophy regarding trying to fix something that isn’t fully broken, Anna offered me some insight.
“Let me show you what I do to get it to quit running,” she said.
She then raised a foot and slightly tapped the gray toilet bowl. Amazingly, as if on cue, the water ceased its trickle.
There are devices whose behavior would suggest they have a “sweet spot.” It’s a “magical” area that through time and trial someone has determined they can touch, punch or rub to get an item to start or stop.
I cite as an example the 1985 movie “Back to the Future.” Remember near the end of the film when Marty McFly is having trouble starting the DeLorean at the appointed moment necessary to ensure he will catch the lightning bolt that is needed to power his trip back to the future? In frustration, McFly hits his head on the steering wheel and the car starts. He found its “sweet spot.”
While my illustration is simply Hollywood fantasy, Anna’s success got me believing there might be some fact to this fiction. But later in the day, as I stood repeatedly bumping my trickling toilet without positive results, I felt a bit foolish and “flush-tered.” Did I simply lack the touch, or was it time to sour on the whole “sweet spot” notion?