I also regularly look at my tires and check the pressures if they look low or particularly when the temps drop in the fall but I did have one case where the TPMS really saved the day. I was driving down the freeway in rather heavy traffic at 65mph and my TPMS came on. For some reason I decided to work my over to the shoulder and pull off. I walked around the car and found a rear tire that looked somewhat low and luckily I'd stopped the vehicle so I could see a fresh screw sticking in the tread. As the tire wasn't flat I quickly got back in the car and got off the next exit, less than a mile ahead. Again luckily their was a tire shop very close to the top of the exit. I quickly made it into their parking lot and pulled in front of a service door, got out and the tire was near flat by this point. I went in the shop, they got me right in and about 20 minutes later I was told they got the screw out and installed a plug and I should be good to go.
I asked how much I owed them and they said nothing! They just said to keep them in mind when it was time to get new tires, nice
So in this case even though I regularly looked at my tires, the TPMS saved the day and saved a possible blowout or having to get a tow alongside a busy freeway as the Leaf doesn't have spare and I doubt the air compressor and can of fix-a-flat would have worked, but maybe it would have but I'd kind of hated to use it as apparently it makes quite a mess inside the tire.
Note after this incident I bought a $5 tire plug kit and put it by the air compressor for just such emergencies.
Oh I also tell people if I see their tire is low, generally they thank me and generally they were totally oblivious anything was wrong