There are three key tips you can follow to make your hot water last longer in relation to your shower systems.
Firstly, you should flush your water heater tank on an annual basis. Nearly every water heater manufacturer would recommend flushing their tanks once a year.
You should also check the anode rod for corrosion, and seek a replacement if it has rusted badly.
Finally, you can insulate your hot water heater tank to make your hot water last longer.