I bought a used Wemo plug for $10 and set it to only be on for 3 hours in the morning and 3 hours at night. Now we have hot water at any of the times when we actually would want it, and we aren't wasting money/energy to keep hot water on tap 24/7.
The problem is using devices that are either timed or (even worse) just runs 24/7.
Ideally you'd want one that runs on demand when triggered by a switch: hit the button, it runs for 30-60s while you undress, and then we you turn on (e.g.) the shower the water is already hot.
The hot water supply for the shower should be the same as the sink, and so when you go to shave or brush your teeth, that's then already primed as well.
Do a search for "Gary Klein", who has written a lot of designing good hot water systems over the years.