I would never use "Depth Chart until 4th". There is a design problem that is not yet solved. Look at this thread of the bug forum:
(26712.1)When you put your best players as starters, it will work very similar to "Strictily follow...".
When you put worse players as starters and the best players as backups, then very often the GE will change your order and put the good backup as starter in the match and he will play most of the match.
So basically you cannot expect to have a rational use of the 4th quarter, because if you put your best players as starters, at the last quarter the coach will still think that they are the right choice and they will play. And the other logical use (setting bad players as starters and let the "good ones" enter the match at the las quarter) is bugged.
¡Me aburro! (Homer Simpson)