I think you may well be wrong about them turning. There's quite a lot
of
vibration, and not a whole load of positivie locking.  Can't see why
the
linkage won't wear either.

In any event, every straight 4 I had ran noticeably smoother after a
balance, particularly at idle, and they woudl idle rougher after about
6
months. YMMV of coruse :)

I have to agree with Catman on this one, I had a 1500cc Sud Ti, & a
2000GTV Although they had Dellortos  they adjust the same as the Webers
and you may have to reset them at least once a year.
You have to make sure the linkage opens all butterflys at the same time
via the adjustment screws on the small cams. Gunsons do a cheap but
handy gauge with a tube to balance these carbs, you have to hold the
gauge onto each inlet port and take a reading then adjust to get them
all the same.
To adjust the mixture I used to screw in all the mixture screws then
unscrew out 2 full turns. start the engine, Then with my ear to each
port in turn, I would listen to the engine note for the smoothest
running while adjusting each screw back and forth slightly, then after
a good road test I would check  the colour of the spark plugs. If they
were light grey the mixture is too weak, if they were brown to black it
was too rich. But if the engine note was smooth while checking, it
would probably be spot on. Maybe a slight turn to each to get the Co
exact at the MOT station.
John, UK.