I wired a webhook to fire on every row insert. Clever. Then I bulk-imported 4,200 leads and every single insert fired the webhook, which fired Twilio.
4,200 SMS in about 90 seconds. $380 gone before Sable's gateway noticed the spike and killed it. I got a 2am call from my accountant asking why Twilio had just billed us like a small election campaign.
The lesson isn't "don't use webhooks." It's that automation without a rate limit and a kill switch is a loaded gun pointed at your own bank account. We built both the next morning.
