"Cabbage leaves work for engorgement." Surprisingly, there's some evidence for this. A few small studies suggest that cold cabbage leaves applied to the breast may reduce engorgement and pain similarly to cold gel packs. The mechanism isn't fully understood — it may just be the cold, or there may be a component in cabbage that helps. Either way, it's harmless and many parents find it helpful.
"You should bind your breasts to stop production." Outdated and potentially harmful. Breast binding increases the risk of clogged ducts and mastitis. A snug, supportive bra provides comfort without the risks of compression. The evidence supports gradual milk reduction, not forceful suppression.
"Once you start weaning, you can't go back." Not entirely true. If you're in the early stages of weaning (still pumping several times daily), you can increase frequency again and supply usually responds — especially if weaning has only been going on for days, not weeks. The longer you've been reducing, the harder it is to rebuild.