As I mentioned just slightly later in my post the issues I've had with preforms (actually self made rings of filler) placed in a joint are when the gaps/fit is not spot on, when brass/bronze is used and that I nearly always found additional filler was needed to complete the joint's full fill.

As to the additional material around the socket's edges of the Goodrich shots I suspect this is to help both heat levels at the shorelines as well as to add thickness that the filler will meniscus up on to. Then when filed off/down the filler has complete joint edge fill. Andy