In three of the five Trek TV series, the first officer has another area of responsibility besides just being the exec. Spock was science officer, Kira was liaison to the Bajorans, and Trip was chief engineer. But when there was an XO who didn't have another duty, like Riker, Chakotay, or even Decker from ST: TMP, they seemed to think that the first officer's role was to be on the bridge at the same time as the captain, acting as some kind of advisor/co-captain, even giving orders in parallel to the commanding officer during battles and such, which is just silly.
They should have had it so that the executive officer takes care of personnel issues, day-to-day stuff, etc. to keep the ship running smoothly for the captain to be free to make command decisions. (they're also too highly ranked to have Riker as regular away team leader, but TOS was even sillier on this point, so oh well) This would push characters like Riker and Chakotay a little more to the background, like the chief engineers in the later series sometimes, who were off in their engine rooms, but at least it would give them a real job other than to be another Counselor Troi, sitting next to the captain and advising him.
They should have had it so that the executive officer takes care of personnel issues, day-to-day stuff, etc. to keep the ship running smoothly for the captain to be free to make command decisions. (they're also too highly ranked to have Riker as regular away team leader, but TOS was even sillier on this point, so oh well) This would push characters like Riker and Chakotay a little more to the background, like the chief engineers in the later series sometimes, who were off in their engine rooms, but at least it would give them a real job other than to be another Counselor Troi, sitting next to the captain and advising him.