Actually, dose reductions don't need to "settle" as increases do.
The depot for the L insulins, especially if it is full enough to get kitty into the 30s, just takes time to deplete. During that time, it can still drop the BG low. As an example, if my Gracie's dose is enough that she gets into the 30s and I reduce her, I have to hold the reduced dose for 4-6 cycles because her depot can affect her numbers that long.
Sometimes it doesn't and the reduction fails. For a failed reduction, you want to get right on it and take the dose back to the last good dose, remembering that the last good dose is not the one that got them in the 30s. So if you reduce, the kitty bounces, the bounce clears and kitty is not back in low blue/green, don't wait. Take the dose back up and that might mean just fattening it.