Again, I think it depends on the level and needs of the team and/or the individual players in question as to how much input a coach should have in the game. Players need room to be creative, to make mistakes, and to figure out how to get things right on their own. Sometimes, though, players get frustrated when they (or their teammates) are making mistakes that cost the team in a game and aren't figuring out on their own how to change it. Does the coach simply sit and watch costly mistakes happen until everyone is frustrated and the game is out of reach?
As for recreating situations, yes, that is what we do, but it's only meaningful if the players realize the situation that is being recreated. You can't always expect to "fix" a problem on the field during a game, but you can CONNECT what is happening on the field to what happens in practice. Addressing it briefly at the moment it happens can either point out the relevance of what has already been practiced ("pressure/cover--this is what we worked on yesterday") or "bookmark" it in their memory to work on in the future ("you're getting drawn out--be aware--we'll work on fixing that"). Tends to help with their recall better than waiting till the next day and saying "hey, remember when you got pulled out of position right before their second and fourth goals and allowed the back-post runner in?" "Um, sure, Coach, I remember."
Sometimes, when things are going wrong, it helps ease frustration when they know someone sees the problem and knows it's fixable.
Foremost, though, should be situational awareness...if someone wants to impress me with their views about "best coaching practices," then talk to me about reading and adjusting to the situation at hand. Learning how to read players and determine, as a coach, whether what you're doing on the sideline is helping and reassuring, or stifling and frustrating, your particular players at that particular moment is a much higher-order skill, in my opinion, than saying "you should always" or "you should never."
