For me the other way around. The larger the unit I send after routers, the more casualties they take.

And sometimes a random man in the unit just falls over and dies, like one who is a bit separated from the main, or one who was stuck near a tree or those who lag behind at a fence. Some of the time, they also die when impacting on the charge against a routing unit.

I noticed a much higher rate of cavalry casualties pursuing routers in RTI Cp I-III compared to RTI 4 or Grand Campaigns.