Like said they balance the load between eachother, and there will always be an amp or two differance, just the way the phase works.
Then you get into 3-phase wich has an even less amount of time between pulses. In 240 you only have 2 pulses per cycle, at 3phase you get 3 pulses, so less amount of time that a device's voltage is lowering.
Wich is why 3-phase is more efficient.
Now all new range/dryers require a nuetral, but still not on air handlers, A/C's, water heaters etc...
