As far as I am observing, car drivers tend to be lousy with their tyre pressures. I have only experienced tubed motorbike tyres where a weekly tire pressure checks are not crazy at all. I am curious how often a car tyre would need checking? I am guessing it would be a longer interval as motorbike tyres have soft sides that flex the rubber during operation. Also, how much it would effect the fuel economy and handling?
With all the cars I've owned in the last few decades, if a tire needs any air at regular intervals, there's something wrong. I've had car tires that haven't lost any pressure over a year or longer.
I don't usually check with a gauge, because that takes more air from the tires than they lose any other way. Thumb pressure on the sidewall will tell you if the pressures are different. Only use a pressure gauge if you think there is something to measure!
Tires should be checked with a gauge weekly and visually before getting in the car.
As they are similar in structure - car tires also have flexible sidewalls so the correct pressure is important.
Wrong pressures will cause poor economy by up to about 10% but as people’s driving changes it is difficult to be precise ie 2lbs low is 3% worse economy is not a given...