That's the job of the mission planner.
And yes, if you are running a mission, you should have a pretty good working knowledge of what has what ENY.
To be honest, i'm not a huge ENY fan.
I've ALWAYS thought my "fix" was better.
I thinkg HTC should tie the down time of things to country population.
The more people on your country, the longer it takes things to "re-up" once destroyed.
The fewer people in your country, the shorter it takes things to "re-up" once destroyed.
I'm talking strat, hangers, town buildings, field ack, everything.
For the low # country, instead of their VH being down for 15min, it might re-up in say 10. For the high # country, if their VH get's dropped, maybe it's down 25min.
MUCH harder to take a field, even with a hoard, when the vh and ack is poping every 10min and town buildgs coming back up much faster (not to mention town/field ack)
Possibly up the # of troops needed to capture a map room based on country numbers.
This would also allow the lower numbered country to pork the hoards bases and stop 'em cold. It would also make re-supply much more important to field captures.
I really don't like anybody being restricted from flying anything.