Fuel tank balance

Roger (K8RI) writes:

Low wing aircraft generally have a set sequence or sequences of
drawing fuel from specific tanks to keep the plane balanced. If I
burn too much off one side (and it doesn't take a lot) the Deb will
get decidedly lop sided. A half hour to 45 minutes per side on the
mains is good. An hour on one side and the other wing will get heavy.
Were I to burn all the gas out of one wing tip tank while the other
was full I'd be in a heap of hurt and I'd want to get the major
portion out of the second tank before landing. The book says no more
than 5 gallons difference between the two.

That's what puzzles me: If you're not supposed to have a significant
difference between the two, why aren't the two tanks just connected so
that they always drain at the same rate on both sides? Why would you
_want_ one wing substantially heavier than the other?

I can see why one might want to change things for fore and aft tanks,
or between center tanks and wing tanks, but I don't see any utility to
having one wing heavier than the other, or to having wing tanks that
don't communicate with each other (provided there's a cutoff for
emergencies).

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