I think there is always a minimum standard of what is "good enough", and everything else is dessert. For example, even though I have access to 30K, I usually only sharpen good quality chef knives to 5K-6K, and low level ones to 1K + a quick CrO2 buffing.

Another issue is maintainability. Again I have access to 30K, but if a customer only has 4K or 8K, then it is unnecessary to sharpen to such a refined level (unless they request it) or to expect them to purchase the equivalent stone.

8K leaves a pretty smooth edge. Everything else is because we can!