Denim jeans were invented to be the pants of hard work: durable, long lasting, and flexible. And most of a pair of jeans do last that long; has anyone ever had the part covering your shin or calf shread? But denim does tend to wear along stress points: the knees, the cuffs, the crotch, and the inner thigh.
If you've made a significant investment in a pair that are just worn in these high friction areas, they can be easily repaired at home. Andrew Chen of 3Sixteen and the Self Edge shop shows you how to fix 'em up good as new in this helpful video:
I love that he essentially just recreates the fabric rather than seaming over the hole or using a patch. Genius.