Especially in Toastmasters, I’ve noticed a tendency to correct someone while they’re in the act of making a mistake.
Don’t we learn better by making a mistake and thinking about it in hindsight?
Interrupting someone as they’re making a mistake can throw off the rest of their speech.
Let ’em fail and be a generous coach afterward. These are two big things that often go unsaid, but we’re in Toastmasters to learn.