As per the title, this is mainly concerned with Bridge Watches and Away Teams, but there are plenty of other examples through all 5 series of "Main Characters Do Everything" where due to the demands of budget etc out-of-universe the stars of the show do things (including away missions) that would be more properly the domain of lesser characters.
As far as Away Teams go, the oddity for me seems to be less the fact that senior officers are going on Away Teams, but rather the fact that only senior officers seem to go on Away Teams esp from TNG onwards (plus Enterprise but it's less jarring IMO on that show as even the senior officers are in many 'rookies'). It seems to me that a standard away team of six (based on the number of transporter pads) should have at most two senior officers, with a junior engineer/science specialist (as appropriate) plus a trio of enlisted security specialists at least one of which should be a cross-trained medic (or a dedicated junior medic if casualties are specifically expected).
For Bridge shifts, it strikes me that in some ways, for all it's flaws, ST:TNG "Disaster" possibly presents one of the better views on what the day-to-day staffing of bridge shifts should be like - one experienced line officer (lieutenant possibly even Lieutenant Commander on a large ship like the Galaxy-class, maybe a junior as an experienced ensign (like Lavelle up for promotion soon?) on smaller ships like Defiant), with the other stations manned by ensigns, acting ensigns, cadets on field assignments, or possibly senior enlisted (O'Brien's presence on the bridge of Defiant suggests this is possible, how likely it would be normally on a larger ship I don't know, does anyone have any thoughts?). Certainly I can't any reason why more than one of the ship's senior staff would be on the Bridge in normal day-to-day business (and that one should probably be in the Ready Room/Observation Lounge doing 'paperwork') and at least a couple of reasons why especially the Captain and First and Second Officers wouldn't be.
On the other hand, most of the 'on-ships' examples of the Chief Medical Officers, Security Chiefs or Chief Engineers getting a bit more 'hands-on' within their specialism are IMO semi-justified by limited personnel in those departments compared to civilian equivalents - especially for the CMO - and them being the 'best' at the job (though many people have pointed out that is wasn't always with Worf).
Sorry if the above is a little rambling, but I'm not very good at expressing myself.
Shamrock Holmes
As far as Away Teams go, the oddity for me seems to be less the fact that senior officers are going on Away Teams, but rather the fact that only senior officers seem to go on Away Teams esp from TNG onwards (plus Enterprise but it's less jarring IMO on that show as even the senior officers are in many 'rookies'). It seems to me that a standard away team of six (based on the number of transporter pads) should have at most two senior officers, with a junior engineer/science specialist (as appropriate) plus a trio of enlisted security specialists at least one of which should be a cross-trained medic (or a dedicated junior medic if casualties are specifically expected).
For Bridge shifts, it strikes me that in some ways, for all it's flaws, ST:TNG "Disaster" possibly presents one of the better views on what the day-to-day staffing of bridge shifts should be like - one experienced line officer (lieutenant possibly even Lieutenant Commander on a large ship like the Galaxy-class, maybe a junior as an experienced ensign (like Lavelle up for promotion soon?) on smaller ships like Defiant), with the other stations manned by ensigns, acting ensigns, cadets on field assignments, or possibly senior enlisted (O'Brien's presence on the bridge of Defiant suggests this is possible, how likely it would be normally on a larger ship I don't know, does anyone have any thoughts?). Certainly I can't any reason why more than one of the ship's senior staff would be on the Bridge in normal day-to-day business (and that one should probably be in the Ready Room/Observation Lounge doing 'paperwork') and at least a couple of reasons why especially the Captain and First and Second Officers wouldn't be.
On the other hand, most of the 'on-ships' examples of the Chief Medical Officers, Security Chiefs or Chief Engineers getting a bit more 'hands-on' within their specialism are IMO semi-justified by limited personnel in those departments compared to civilian equivalents - especially for the CMO - and them being the 'best' at the job (though many people have pointed out that is wasn't always with Worf).
Sorry if the above is a little rambling, but I'm not very good at expressing myself.
Shamrock Holmes