Long waits are more common than you think. Suppose you have 100 feet of 3/4" pipe and a 1 gpm showerhead, it takes 2.3 minutes for water to move from your water heater to the showerhead. And you not only have to move the water, but heat up the pipe itself, so it takes even longer. I'm living in such a home now. I'll be installing a recirculation loop as I remodel. And probably some point-of-use heaters.