I have always ran my .65 on muffler pressure.
Very consistent runs the whole tank. The last plane it was in would give my over a 3/4 hour run time using modest throttle. The plane was sort of a copy of a Kadet SR, but made with foam board (and balsa). A real nice low speed flier. I mostly shot a 3/4 hour worth of touch n goes with it. It was just to much fun that way. So in general I seldom used more that 1/ throttle, even on take off. Just to much fun exploring low power end of the flight envelope. Lost the plane in a same channel shoot down. Must have been at least a 16 ounce tank. I think a 14-5 prop (maybe smaller, long time ago).
But the engine sure performed sweet on that plane. Yanked the snot out of too if I got into throttle.
I think the last time I did not use muffler pressure on my engines was the old scavenge ported engine that did not even have mufflers. I just dated myself.
Ken