it seems as if a unit suffers heavy casualties they will gain ranks quickly.
not sure exactly why it happens. since the times of RTW, unit experience has been generally the average of all the men in the unit. if a unit of 100 soldiers were very experienced, and 70 died, upon being retrained the experience of that unit would be reduced since the 70 fresh replacements brought the average way down.
in NTW, while your unit is being replenished, the experience stays the same. i am guessing that the high amount of sudden experience after suffering casualties is due to the experience of the survivors since they now make up most of the average. replenishment doesn't reduce this high experience when the unit is filled with 'new recruits'.









