I think it takes the confidence to let your baby dictate when they have had enough under either method.
My friend BLWd and offered food every time he cried, I can see also how that can lead to an association I'm unhappy - EAT
And with traditional not listening to the babies signals they are full.
Luckily for me, DS starts waving his arms around and spitting food out when he is full so it's not hard to judge.
(Thorin under a NC by the way not being a sock puppet or anything!)