I'm not sure I understand what you mean by 'ledge'. If you mean you can see and feel a sharp 'ridge'? Are you letting any flexcoat go from the wrap directly on the blank?
I generally let it go 1/16" at the very most extend unto the blank. Just move the brush over enough to do this, something to brace your hand on helps keep an even line. I feel this 'locks' the thread in better and makes a smooth transition from one to another.

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To fish or not to fish?
What a stupid question.