Sounds to me like one smart cookie who has been around puddle jumpers for a while. I would not be surprised to learn that this titbit had been passed down a few generations: and guess what....it continues to be passed down.
In my days with low wings a/c it was common, on the walk round to peek into the tanks. One great difficulty with high wing. I'd be curious how both fuel sensors/gauges could be wrong. Take off with L/R selected is one thing; stutter and change tanks, but for both gauges to show an erroneous amount is smelly.