325d service

[Fishmoint]

Had my 325d m sport about 8 months now, I don't do a lot of miles when I bought it I put it straight in for a full service at a local indy, the guy is german and has worked at bmw dealers, one thing that I've never heard before was he said he has filled the oil to three quarters on the dipstick and I should never top it up to the maximum mark, has anyone else heard of this or know why or what could be on his mind for this way of thinking?