Fields of Despair - GMT P500.
Is there anything to stop the non initiative player in action phase 2 of a turn emptying the front line to concentrate his forces in attacking a few hexes and then Strategic Reorganising them back to re man the frontline?
The simple answer is yes, this move could be attempted. It's not as effective as it sounds except maybe in a learning game.
Taking 1914 for example (Allies are non-initiative),it's important to know the potential for the move going in because it keeps the Central Powers from going all out on their turn. It forces the Central Powers player to make sure the lines are solid and not populated by 1's.
Keep in mind movement limits and restrictions for contested hexes mean blocks can't move very far to attack. Given that lines are generally long, strength is spread out, so even a concentrated attack is tricky to pull off esp with good air recon. Further, if the initiative player holds Logistic Points (highly advised) for reinforcement the move can be countered.
If the move works, it's often a combination of poor luck with air recon, a thin line, and/or a failed risk taken (by the initiative player) elsewhere on the map.
Also note, completely abandoning a hex changes control and thus the non-initiative player cannot Strat Reorg to that hex.
I know this has caught some first time players by surprised and soured them on the game. Hopefully the thoughts above help.