Hi,
TW is a turnbase game so you always have to wait to your turn to be able to react to any move the AI make in their turn, and same for the AI . That's why blitzkrieg always works.
You can notice there's a zone ( around any army or fleet )that if an enemy army ( or fleet) enter that zone, you can choose to let them in or attack them with that army ( or fleet ).
My idea is to enlarge that zone to their movement point ( from the previous turn of course ), if you can make it in time of the battle, you are in, that's reality.
That way the game is much more realistic, for example: allies will be involved more often in battles, naval invasions now are harder since the AI will defence their coast more effectively, invasions now are not just capture the enemy capital , you have to deal with all their forces , even their allies, etc ...
How about that ?