The fuel gauges on the Bulldog were notoriously unreliable. I once had a delayed recovery from a spin to the right which surprised me as the gauges indicated perfect balance and the student had applied precisely the correct tehcnique.
A few months later I was reading another QFI write-up on one of my students (a different one), in which he'd criticised him for poor spin recovery. That surprised me as I though he ws pretty good.
It turned out to be the same aircraft, so I demanded that the fuel gauges were checked. They were found to be reading incorrectly! So all the dutiful fuel balancing to achieve a < 3 gallon imbalance had just made things a lot worse.
If you took off with both tanks full, kept the selector on 'both' and ensured that the ball was in the middle throughout, you would probably have a much greater likelihood of correctly balanced fuel than relying on those lousy gauges!