Argento budget question

I've just been watching the documentary Italian Kings of B, which has a brief segment with Tony Musante. He says The Bird with the Crystal Plumage was sufficiently low-budget to be made with ends of film stock, and that Argento would say cut as soon as he felt a scene was done, while Storaro would keep shooting if there was something that interested him. What do you think is the truth of this? I'd be inclined to disbelieve him, that even at this point Argento wasn't exactly the Italian equivalent of poverty-row, but is / was buying ends of film really such a rarity for a first-time director, or a lower budget production? (After all, didn't the spare wood left behind by Lawrence of Arabia furnish spaghetti westerns shot in Almeria?)

And, indeed, does anyone have a sense of who are reliable sources and not in Italian popular cinema (e.g. Fabrizio Jovine as someone who the Lucio Fulci Remembered DVD people found to be a ‘key informant’), or anything to do otherwise triangulating sources?

The documentary itself is great; I just wish there was more of it...