In Rugby they often select players specifically to start games with the expectation that they will be replaced after an hour. With the game being so physically demanding it allows players to provide peak performance for a shorter period before being replaced.
I think that with the increased number of subs available we will see more of this in football to either prolong players careers with those like Josh McEachran, or to help introduce younger players.
McGuane was our best player fir the first half of last season playing in a deeper role so I'd have no issue with him coming on as a direct replacement for McEachran either when he's knackered or if we need to add a bit more energy into the team.