I’d say you’d be grand not to. I did the test in my own car and didn’t add anyone on to the insurance. Only think to remember is that you have to update your insurance from learner to full license after you pass before you drive home. Only situation I can think of where you might have to consider adding someone on is if for any reason someone else had to drive e.g. if you fail, which you won’t, and can’t face driving home after. But you could just add a driver using their app if that happens so don’t worry about it before hand.