The phrase from the letter to Meoceus that we don't want the longest life but the "most pleasurable" certainly is relevant, but something has to show that it isn't sufficient to fill 100% of our locations and durations with sitting in a cave staring at the wall. That intuitively is not sufficient but if accepted would make intensity irrelevant - just as expanding any one of the three exclusively would make the other two irrelevant.
Duration, location, and intensity must have some kind of natural status of importance that requires consideration of all three.