Riley adores his food,he practically "inhales" each meal of jwb, he has the duck, lamb and fish, we have two flavours on the go at any one time. He is quite greedy so doesnt prefer one over the other, or at least he doesnt show it.
I would have thought rather than flavour changing causing fussiness it would be actually complete change of food, also adding "nice tasty" bits if they are a bit fussy, would have thought that would have made them more picky, not changing the flavour though.