I've been a Bernina owner for well over 20 years and they ALL are oil thirsty in my opinion.
I have the 780 . . .and I add a couple drops of oil under the throat plate, every time I refill a bobbin (also change needles at that time as well). Every other time, I also oil the bobbin assembly on the designated dots.
These machines have huge bobbins, comparable to my M class bobbins on my midarm. Oil and needle change with each bobbin fill really isn't all that extreme, IMHO . . .and she purrs.