Opposition Instructions Question

Hi all, first of all I'll admit that before i got into FM I wasn't a huge soccer guy (FM is actually one of the reasons I love the sport now), so maybe the reason I don't know this is my lack of soccer tactical expertise compared to some of you guys, but anyway, here goes:

I've always wondered, in opposition instructions, wouldn't it just make sense to close down/tight mark/force to weaker foot EVERY attacking player on their team? Wouldn't that just make for overall better, tighter defense against their whole team, rather than just focusing on a couple guys and going easy on the rest of them?

Has anyone tried this? I guess the reason you wouldn't do this is it would tire your guys out faster, and possibly be vulnerable to an attack if one of them got by you when you were tight marking or closing them down, right?? In extreme situations would it be worth it though?

Welcome to the sport, I got some friends in Vancouver...

Closing down everyone can pull your players out of position, take for example your right back, he might try to close down the left back (his opposing player) and the be pulled away from his main task that is to mark their left Midfielder and leave his area on the pitch exposed.

What I find to be good for my teams is to have the attacking players close down all over the pitch as I don't have the ball they are spare, but to leave my defender and midfield to only close down in my half, this help maintain the structure of the defensive unit.

If the other team has a real super top class player you could try to use a player to man mark him, but I find that the opposition instructions get in the way of how I set my tactic to work.

The real key is to make them try and get past your solid defense, don't make it easy for them by moving out of position to often. Have fun...