In reality, nurses are almost unheard of on frontline naval vessels and doctors are fairly rare (limited to the largest vessels like amphibous vessels and carriers recently, and cruisers, battlecruisers and battleships historically), with Independent Duty Hospital Corpsman (essentially highly-skilled military paramedics/care assistants) doing most of the medical work.
In Starfleet, at least one doctor is typically posted to much smaller vessels (probably small multi-role vessels of Saber-class or better, and combat vessels of the Defiant-class or larger as they come online (probably equivalent to no more than a frigate)), with two or more on long-range explorers) and nurses are at least as common. Looking at evolving developments in civilian medicine, I would assume that that nurses act more in line with primary care physicans (or British GPs) and treat most of the routine medical conditions that sensors can identify automatically (with the assistance of the technicians), whereas Medical Officers act more as diagnositians and researchers (for conditions that the system can't identify the condition or treatment) and also as surgeons when physical damage needs treated.
Does that make any sense?
Shamrock Holmes
In Starfleet, at least one doctor is typically posted to much smaller vessels (probably small multi-role vessels of Saber-class or better, and combat vessels of the Defiant-class or larger as they come online (probably equivalent to no more than a frigate)), with two or more on long-range explorers) and nurses are at least as common. Looking at evolving developments in civilian medicine, I would assume that that nurses act more in line with primary care physicans (or British GPs) and treat most of the routine medical conditions that sensors can identify automatically (with the assistance of the technicians), whereas Medical Officers act more as diagnositians and researchers (for conditions that the system can't identify the condition or treatment) and also as surgeons when physical damage needs treated.
Does that make any sense?
Shamrock Holmes