Actually, it does work that way. I have a friend whose father owned a Sunoco station a very long time ago. Sunoco stations used to have many different octanes available from the same pump simply by rotating a selector on the side of the pump. All it did was change a combining valve that pulled different ratios of the highest octane with the lowest.
I've have made a habit of putting 93 octane in when the tank is close to empty. I top it with 89 when I need less than half a tank, and I know the last full fill from empty was done with 93.
I have never experienced knocking, and my milage is not affected negatively.
I have been driving Hondas probably since before most of you were even born. My first was a '75 Civic with a CVCC engine (3 valves per cylinder to reduce pollution).
Blending is perfectly fine. Yup, I saved all of 60 cents on my last fill from one half of a tank, but there is nothing wrong with doing it.
