The main reason for turning the engine over is to keep the bores coated with oil so they don't rust. The bearings are pressure fed and should retain some oil so are not really at risk of seizing up.
Provided the engine was properly warmed up the last time it was run, and it is stored in a dry environment then there's not much benefit from turning it over every couple of weeks. You could go to the extent of "winterising" the engine by putting a few drops of air tool oil down the spark plug holes and turning the engine over a few times, but that may cause the plugs to foul when you go to start it up.
FWIW I Just started my Holden after letting it sit for 3-4 years, started after about 3-4 turns and run smoothly, even with 4 year old fuel. Although thats in an airconditioned underground carpark in Australia and the humidity rarely ever gets over 20%
