Going back to the job title and when you can call yourself what (as someone brought it up recently), it’s often fairly nuanced and context-dependent. I’m a doctor. Not Doireann. I have dark hair and a fat bottom. And my house is really messy.
I’ve heard senior surgical trainees who would operate independently (fairly reasonably, in my view) say “I’m Mr X, a surgeon on Ms Y’s team.” Some specialities, it’s more common to call yourself the title once you pass membership exams. (I’m not a GP, but if a person passed the MICGP exams, you may be MICGP before finishing a training scheme. You certainly would be MRCPsych in psychiatry or MRCP/MRCPI in general medicine.) If you’re a surgeon, you can technically call yourself Ms/Mr after passing MRCS/MRCSI, years before consultancy.
You could also look at it from the perspective of training stage. In some areas, later stage trainees are doing the job. Again, I’m not certain how GP works, but I do know that year 3-4 a person is working in a practice full time and seeing patients independently. They might call each other GPs. My boss used to refer to me by my specialty as soon as I’d committed to it, but I’d plenty of experience.
Final thought for now, not every doctor who isn’t a consultant is in training. Many have full exams, but not necessarily a formal training scheme. In the UK, you could be a staff grade XYZ, but it’s not as common here. I’d happily call someone with exams and 20 years of experience a cardiologist, for example.
(May be rambling. Very little sleep. My sleep hygiene is not as good as that of some.)