I would not stagger the opening of the TB's to inccur fuel millage or performance. The efi system should be the tool you use and not the TB for tuning. You will limit or increase air flow hoping the efi will compensate, and it will to a point.

You will have to run the correction limits wide open in order to allow it to compensate, and they typically max out at +/-20% from VE...So anything outside of that, assuming you got VE dead on for the set-up you have it on now, and you have just leaned out or richened the engine out, and the efi cannot compensate and it runs like crap.

The correction factor is the difference between the VE you have programmed into the table and the programmed target A/F...The efi system will compansate the base VE number to achieve the target A/F, assuming you know the right A/F for your engine. Now, when you change the air flow, the VE in the table will be off, and the compensation factor the system needs grows to hit the target A/F. Now under normal conditions, that factor is used to compensate for air temp, humidity and elevation, now you want to throw in the TB.....Well, that only leads to running like crap considering how much you can change it with no less than three TB's.