I recommend using it. But remember it looks at 1st half stats, NOT ratings. For ex., If your avg on def - your set to "0" - the other team is leading all of Div I in 3FG attempts and 3FG% - but in your game the other team is unlucky (it could happen!) and shoot 1 fer 13 from beyond the arc - well, in that situation the sim engine will see the other team is scoring mostly from the interior and adjust your defence to "-2". This might not be a good thing.
So I don't recommend it. But you can lessen the bonehead stuff (see ex above) by using the "adjust only if losing by 5, or 10". Also, when you start a game against a better opponent and you try an extreme "+" or "-", halftime adjustments help when you guess wrong. Which is why I recommend it.