Isn't that the sheeting in post 6? I think he saying the fillet will shrink and cause a visible line on the outside, maybe I misunderstood what he was talking about? I never noticed the effect but it makes sense.
I don't worry about adding fillets, I believe you're better off getting the glue between the parts rather adjacent to. Fillets are sometimes necessary when the fit is not so good.
I would not use Tiebond III either on the complete build, only where strength is an issue, I find it doesn't sand very well or at all. White glue is all you need for most parts.