The penalty is rather low though, and in my experience no one particularly ever cares to exercise credits unless it's something egregious, so provided you're no

The penalty is rather low though, and in my experience no one particularly ever cares to exercise credits unless it's something egregious, so provided you're not consistently below 99.9% every single month (which is pretty bad even for a startup), it's generally pretty safe to assume a little bit of a risk if you only miss it occasionally. Bigger customers will absolutely look for 99.9%, and anything less will be a huge red flag during procurement.