As pps have said, some GPs do feel very much taken for granted and don't like to say no even though they find it very tiring - and perhaps restricting as regards being able to go away, etc
My neighbour has her gs two days a week, 8am - 6pm, and also her gd one overnight a week as the mother does a night shift, so 6pm - 8am.
She's mid-fifties, quite fit and a keen walker with a rich social life.
Or was. She's been doing this for two years now and it's affecting her mental health - being unable to enjoy her retirement now that her own children are grown up and having her own pursuits seriously curtailed. A couple of times I've seen her in tears of frustration at the lack of freedom she feels obliged to endure.
She doesn't want money. She has a brilliant relationship with both her gc - but would much prefer it to be as a family setting, evenings or weekend visits with parents there and not the drudge of enforced childcare week after week as it currently is.
She wouldn't dream of withdrawing the care, she fears it would cause upset. She once mentioned to her son that it was difficult to go shopping with her toddler grandson and his reply was that, once the child started school, she'd only have him for an hour in the morning before she dropped him at school, and then a couple of hours in the evening after she'd collected him - the rest of the day would be free to do what she wanted.
I was speechless.