For me, full pool is as high as you want the water to be in a semi-permanent timeframe. Many people have a thru the dam drain device which begins to, as Brettski describes, exit the pond at full pool. It doesnt bother that it rises above this for short periods of time, but not stay that high for longer periods. Example, above full pool, the water comes out of the basin in the shallow end, covers vegetation and small fish have a very shallow refuge. If it remains that wasy for too long, not good for the looks surrounding the pond, or for larger fish being able to forage.
All that being said, it sure is nice to start out the spring with the extra water. Especially, for me, this year.
DID I OVERTHINK THIS, OR WHAT?