Like if a custom maxTools amount or player model was being used for one datablock, but then after being over-encumbered, they revert back to the standard maxTools / player model with the encumbrance datablock.
However, I've decided just to use custom player datablocks anyway, instead of using zones; it might not be that big of an issue, plus I can revert the player back to their previous datablock if they are no longer over-encumbered (even if the maxTools amount changes, they don't loose items in their tools inventory when reverting back, which helps).