We currently only have one bathroom and one guest toilet and would never plan it that way again, or in our new build there will definitely be an additional children's bathroom. With small children, one bathroom is not a problem but not when they get older. There is constantly knocking on the door, both children naturally want to use the bathroom at the same time, no one wants to get up earlier, there is complaining about unauthorized use of each other's toothpaste, shower gel, etc.... that's just how it is with children going through puberty. Earlier, we couldn't have imagined it being so stressful with small children either, but now we are very much looking forward to the additional bathroom.
Best regards Sabine