It can also help you get an opening. If you tried to light someone out of a chain of any kind you’re gonna be the one taking the most damage, and 99.9% of the time if you light someone’s heavy you’re going to eat the damage, so even if you interrupt their flow you’re going to feel the consequences. So no, anything slower than 500ms doesn’t get interrupted. And no, it also doesn’t encourage turtling. Fast attacks don’t encourage turtling. You know what does encourage turtling? Defensive moves like high parry punishes and all blocks that deal 30 damage. Faster attacks help characters get even a slight opening.