More than ten is too many
Human beings suffer from scope insensitivity.
Time and again, we're unable to put more urgency or more value on choices that have more impact. We don't donate ten times as much to a charity that's serving 10 times (or even 100 times) more people. We don't prioritize our interest or our urgency based on scale, we do it based on noise.
And yet, too often, we resort to a narrative about big numbers.
It doesn't matter that there are more than 6,000 posts on this blog. It could be 600 or 60. It won't change what you read next.
It doesn't matter if a library has a million books instead of a hundred thousand.
It doesn't matter how many people live without electricity.
Of course it matters. What I meant to say is that when you're about to make a decision of scale, right here and right now, if the number is more than ten, the scope of the opportunity or problem will almost certainly be underestimated.