No I don't always discharge down to 50%. Generally we recharge each morning then again early evening.
We have a 240v fridge and a diesel fired heritage range which provides cooking, heating and hot water. The range is on a timer just the same as a domestic heating system so this along with the 240v fridge means that the inverter needs to be on 24/7.
Over time I've found that if we recharge every evening to 90% or above by morning, post breakfast/washing up/morning ablutions /heating on/hot water etc the batteries are down to about 60-70%. Over the past 3 years I've found these figures to be fairly consistent with seasonal variations. We usually try and give the batteries a full float charge once a fortnight usually after cruising.
However there are occasions when the batteries have discharged to 40-50% when we've had weeekends away for example. On these occasions I usually give them a good 8 hr recharge up to and beyond the charger switching to float.