I’m sure that in the interests of making the patient more comfortable, dosages are exceeded
That may be the case now in the UK where doctors can use their discretion.
But I’m sure you can appreciate that when assisted dying is introduced, that comes it with very fixed limits on what levels of morphine are acceptable; for obvious reasons the state has to define what dose of medication causes death and then tight legislation is drawn up to create stricter lines around what is a dose intended to euthanise the patient and what is a dose for treatment and pain management.
If you assist someone in dying then that automatically requires clarification around the doses necessary to do that. This is so there is a strict division between the team providing help with dying and the team who are treating a patient. And this is necessary because otherwise medication can be abused or in case the procedure didn’t work or something went wrong and there is an enquiry.
Doctors in the country where I lived were upset when they couldn’t give patients they had known for a long time, the pain relief they required to make them comfortable at the end of life, for fear of being prosecuted themselves because it went over the fixed limit for treatment. If it went over the fixed limit then then they could be accused of entering assisted dying territory unlawfully.
In summary, by allowing assisted dying you have to create a detailed legislative pathway for that, that covers all eventualities, and by creating that pathway, it means a separate one is created for those who do not want assisted dying, and the levels of meds needed for both pathways are more tightly regulated.