Ours is an Alde system where the water heating is integrated with the space heating. Summer or winter, on gas or electricity we leave it on whilst actually out caravanning, but off for transit and stowage. Did the same with a separate Truma boiler in an earlier van and Carver before that. Always take the view that is what we want hot water when its needed, washing after using the loo etc, just as at home we have hot available 24 /7.
Only the Carver gave up but that was a corrosion issue with the tie rod, nothing I linked to use, just appalling construction relying on an epoxy coating for protection even on a screw thread.