One of the things I took from the articles is that simply dusting the food isn't going to do any good all by itself.

As for whether you should dust every feeding or not....... I'd dust every feeding. But I'm not an expert by any stretch of the imagination. I'm just working on the idea that if you provide a mega-dose of something, then they should at least be absorbing a little bit and possibly a beneficial amount from that dose.

I don't know of any down sides to dusting every feeding.

But I would highly recommend you get a UVB emitting fluorescent bulb and try to ensure that the affected fbt as well as the others are able to get within the distance of the bulb the manufacturer shows the correct strength of UVB will be received.