Every unit would need to be weighed on whether it would be better denying the enemy victory points by killing, or retreating as quickly as possible. If a powerful unit can kill 2 weak units, then it's already both made back the VPs it might lose by not escaping and denied the enemy 4 potential VPs, and with a turn 1 charge available, that powerful unit is not going to struggle to kill something. I don't think either full retreat or full attack would be viable strategies compared to using stronger, slower units to take out and screen enemies while weaker, faster units retreat.