Not to belabor the obvious, but ILF bows, like all bows, need to be returned whenever you change arrows, or change the length, overall weight, or FOC of the arrows you are already using. Sometimes if you buy the same arrows you're already using, they can be enough different to require a tweak in the tuning. If you change your form, it could change the tuning. Ken Beck advised us in a class one time to carry a bare shaft along when we practiced and shoot it from time to time to see if there were any unexpected changes to tuning.
ILF bows contain more adjustments than non-ILF bows, and those adjustments should be checked from time to time to see if they have moved.