Well I'd advise to change them whenever you can.

As you may know same attcking corner settings should work differently with different formations, but I found this during my latest test in MR. L's testings league with CA145 team while testing FALCHION V3.
MCR should take the corners!


Actually the thing is change is constant, you have got to change a set piece routine whenever you are seeing the opponents are doing well against you, here in this routine its quite efficient I had it in my tactic too I make them myself and you should do it too in this setup suddenly change those at the posts to the 'go forward duty' you will see loads of goals for several games, then again change it to default, and thats how you do it, the main thing is corner taker and change the instruction to 'mixed' and if you have good tall players in the box try to have as less people as possible in the box, bcz congestion makes it difficult for other players to make use of the pace, if you have 2 good CBs with lot of heading power, dont put other players forward much, put only max of 2 more players you will get loads of goals, heck even you could get 4 corners goals in a row in a match, so change it whenever you are not much scoring like before and also I'd advice to put a good decision maker to 'lurk outside the box' with descent long shots(if available) cz they usually tend to get a lot of space and with good technique and all the time in the world he can get a goal or 2 from the long range. Try changing every 7-8 games, you will get much more goals than you'd expected..