Good idea! I am also using kind of pattern for deployment for visual satisfaction. It goes like this:
Lights - without specific order, same goes for archers, slingers, barbarians and cavalry except heavy.
Auxillia - two rows but vertical (to keep the cohesion while moving

X X
X X
Medium and Heavy infantry - close ranks in solid block
Heavy cavalry -
X
X X
(it is the elinistic style cavalry breakthrough)
Once some blocks are lost, I am always taking them from the back rows, trying to keep the front line intact, which is more reasonable than it seems, keeping in mind that it represents the cohesion lost.