The hot water supply has been impacted by the change in lifestyle, the increase in the size of homes, and the increase in the number of plumbing fixtures. In the good ole days, someone was always home running the plumbing fixtures on a periodic basis. The hot water always seemed to be there after a few seconds.
Today, we disappear from our homes for hours at a time. When we return, we turn on the hot water at the most remote location and wait, and wait, and wait, for the hot water to arrive.