With the constant field increases from the IDT maybe this limit of /10 is out dated. Maybe it should be open ended as the fields from the IDT ain't restricted to a certain number. So I feel that this upgrade should be changed to reflect the new concept of receiving fields from the IDT. We should be able to purchase them constantly as well.

Maybe it should be purchasable as

+10 Fields but you select the planet you are wanting those +10 fields placed. Instead of across the entire Empire. This way it would better situated to be applied to the game just similar to receiving them from the IDT. Except a player would have the option to purchase them constantly just as you receive them constantly from the IDT rolls.