The reason people say that a watched pot never boils is that for almost the entire time that you’re looking at the pot, it’s not boiling. Even so, you still have to do watch the pot, because once it is boiling, you have to act fast or it will boil over, make a mess, and maybe burn your meal. Watching the pot is pointless – right up until it isn’t.
It’s the same story with tyre pressure, unless you have a tyre pressure monitor. Usually, when you check your tyre pressure, everything is fine, and you’re left feeling like you’ve wasted your time. But when everything isn’t fine, the consequences can be much worse than a bit of a mess on the stovetop. Under-inflated tyres are a serious problem. They have less traction, which means longer stopping distances and a greater likelihood of losing control of your vehicle. The rubber gets dragged more against road, wearing your tyres out faster and increasing the risk of blowouts. On top of this, balding tyres have still worse traction.
So you need to check your tyre pressure regularly to guard against these problems – unless you have tyre sensors to do that job for you. A tyre pressure monitoring system is the vehicular equivalent of those sensors that turn off an electric kettle once the water is boiling. With a light and an alarm, the system alerts you when your tyre pressure is too low. That way, you can take immediate action when you need to, and you don’t have to worry about your tyre pressure the rest of the time.