I figure there are a few philosophies. Anytime gives your team the ability to be flexible even with a lead. When losing and when losing or tied allows you to make the key switch which might flip a game in the second half. If winning, I have never used. Then there is losing by 5 or 10 or more and then Never switching. I don't use Never, but I can see why that would be useful if you feel strongly enough about your game-planning. 

By and large, I have used "When Losing" and "Anytime" with anytime more lately because I think that most games against good teams are won by winning one half bigger than they win the other half, so your team is more of a moving target of how we are going to be playing from one half to the next. When losing I use more in a defensive gameplan. 

How do you use the halftime adjustments?

 I look at the strength of the opponent and ask, "What halftime score would satisfy me?"  I then set the defense accordingly.   The one I use most often is "if trailing by 5 or more'

It's a tough call, I wish they did it like they do in the GD game where it actually stops at halftime. If you're losing 22-17 at halftime, it most cases you're probably playing good defense. Sometimes it can create a worse situation by using this feature. They really should base it on number of points given up after the first half or field goal percentage since it just pertains to mostly defense. This would be a nice addition if they could add it.

To answer the question, I will use it. If I'm losing by 5 or more, it's worth the gamble to try to change things up.

I have seen too many games where a switch in defensive philosophy flipped a loss to a win, or a win to a loss, and would be very happy to be able to change it up at halftime (as is available in GD).

I use "when trailing by 5 or more" on the positioning of my defense. I keep the tempo auto-adjust switched to "off." If I'm not pushing the pace, theer's a reason for it and I sure don't want the bucket of bolts that is my assistant coach planting the wild hair in my guys that we can run with superman or something in the second half. (I address slowing things down via "when winning by...run...offense at....tempo" area.