Now, the server does this lets say every minute, so you have a window of a minute to run in, manually shoot, and run away.
If you want to reduce the shoot and scoot window down to 30 seconds, you have to double the server update rate from every 60 seconds to 30 seconds. That'll be 100,000 queries every 30 seconds now, so 200,000 every minute. Effectively doubling it.
I kinda disaggree with this the server could check if the enemy army "on shoot command" has arty (or other ranged units) to retaliate and automatically issue a retaliate decision. This would not need to be looped it should just get a flag "if they fired on me.... then I must have been in range to fire back"...