I have implemented a couple of "house rules" that may be of interest to some:
If a unit takes five hits, it must retire directly away from its tormentors a full move according to the formation it was in when it took that hit. If there is a friendly unit in its way, that friendly unit is interpenetrated, takes a hit and may not move when its turn comes to move. Subsequently the "done for" unit is removed at the end of the turn. (I hope I got that all right.)
1. The routing troops do not move in the formation they were in, but at their fastest speed. They're running away! To the underworld with the formation!
2. At the end of the turn, they are not removed from play. They will continue moving to the rear until they are clear of all friendly troops. On all turns after the first they will not interpenetrate other troops, but they will stream around them. If those troops cannot move forward without interpenetrating the fleeing troops (presuming they do want to move forward) then they cannot move forward.