In the early turns at least the AI is focussed on filling gaps in the line (a decent strategy to be fair) It calculates this based on the position value of the hex. The XVIII corps deployment area is huge (the northern half of the map) and this corps gets quite a few reinforcements in the early turns (along with V corps of course)
If when you have finished your activation and you draw an allied card you can be in a position where you are “proximate” to a position hex which is in XVIII corps deployment area and away from your main thrust then the AI will choose this position (as long as you aren’t proximate to high position value hexes in the axis of your main push). So pushing forward to Manhay meant the AI deployed 2 units of the 82nd and one of the 7A there rather than in my way up towards Trois Point because I made sure to be proximate to hexes with decent position values in them.
The second thing to bear in mind is that the AI will make an Allied reserve check when you activate a unit adjacent to a roadblock. If your infantry units pushing westwards towards Bastogne fails it’s roadblock tests then when you next activate that unit the AI will deploy a reserve on it. That’s another reserve unit out of the pool that can’t get in your way further north and won’t be present for undetected defender tests when you try and attack elsewhere.
It’s not a perfect strategy (relying on the dice rolls of course) but it does simulate a “feint” attack quite well…