Is it cheaper to leave my immersion heater on all the time or to switch it on twice a day when the water is co

Question

Hot water is needed for 2 baths a day and to wash and do washing up.

Answer 1

I am putting in a new heating system, should I have it zoned for Hot Water, separately.  Somebody told me that they have their immersion heater on all the time, that this is a cheaper way to operate. Secondly which zone should I put the heaters in the bathroom.