The only time you can have too much fuel is when you are on fire!
John Deakin has a good go at that one in one of his topics.
"Pelican's Perch" Index
Pelican's Perch #7:<br>Run That Fuel Tank Dry!
There's some excellent excellent stuff in there. There are a few things that go against what most people would have been taught, but his reasoning is always very good. If I was ever in a position of overseeing an operation (CP, CFI etc) I'd have a careful read through his works for useful pieces of goodness.