When to use Arrows

I am interested in people's opinions as to when it is approprite/beneficial to use arrows on players. I generally understand how certain formations are better than others, based on how each defensive player counteracts attacking threats in various positions, but I am not sure how arrows fit into this equation. I tend to either use no arrows at all, or just what 'feels right'. For example, if I have a DML and DMR and no other wide players I tend to give them forward arrows, because that is how they would likely act IRL. However, real life comparisons are not always the best at predicting in-game behaviour.

Which of you smart people have profound insight into the use of arrows? :)