My lesson came via my commuter. I'd typically pump its tires to 65 psi, then just ride until it felt squirrelly. Usually that was a few weeks and 20 psi. Eventually I recognized that just before squirrelly was another feeling - luxurious. 30 was the sweet spot on that bike, running tubed 38s. So i went with 30 and aired up more frequently. Probably risking pinch flats with my 200 lbs, but my commute is paved and smooth.