I don't see the "little bit of everything behaviour".
1 mass driver, on a planet with everything.
Sends 10 duranium and 4 neutronium per 1 day tick. (I play with 86 000 time step)
This ratio is exactly the same no matter which planet the mass driver is on. Home planet, my manufacturing planet, whatever. All the same, 10D 4N per 86400 seconds.
Only when Duranium is out then it switches to Neutronium and the next one and so on.