Because for example the Default instruction when given to a MC will take up a different position when a corner is taken to that of a MC with an arrow also on Default.
My corner routine involves having two MCs on Default as they position themselves ahead of the players on Lurk but behind the players that the ball is aimed for and score most of my goals. Giving them an arrow messes up the positioning.
As for free kicks, defensively just make sure you've got the majority on Man Mark, a 3 man wall will suffice and one or two on forward ready for the counter. Attacking free kicks have one or both your centrebacks going forward, either both on forward or one on Keeper and aim the ball for Best Header. Have you're attacking players on forward but keep a central midfielder back and your fullback on Back If Needed.
Now for corners, in a default flat 442 the following setup is a guaranteed way of finishing top of the scoring charts, however you have a diamond formation so a little tweaking may be required for your DMC and AMC.
Have your fullbacks on Back, one DC on Keeper and the other Attack Far. You're bigger striker on Attack Near. These are the 3 players that score all the goals, to be more specific the DCs get the majority. Now have your wingers taking the corners, so when you've a corner on the right have your left winger takes them (presuming hes left footed, always go for in-swingers if possible) and have the other winger on Lurk and vice versa, so both wingers are on Lurk so when one is taking the corner the other is waiting on the edge of the box.
So you're left with your central mids and other striker. Now I prefer to play with one striker but when playing with 2 I put the little guy on Short Option to keep him out of the box because that's the key to cracking the corners in FM08. Now I would either have A) Your DMC on Back if Needed and the AMC on Attack from Deep or B) DMC same and AMC on Lurk. Depends on your team and players really.
Finally, aim your corners to 6 Yard Box :thup:
Believe it or not that was me keeping it brief on set pieces, I really do spend too much of my FM time on setting them up
Corners, Free Kicks and Throw Ins 
Linear Mode
