I guess that is possible. If you are running the proper mixture of antifreeze, then you could cycle the valve, monthly, weekly, whatever. That should help. If you flush the system, open the valve to flush the heater lines and core also. I don't think you would have a problem with all that.
As I stated before, I'm not a mechanic. This "fix" was recommended by an independant Mercedes mechanic in town, who was recommended by a friend.
This friend, by the way, is selling a pretty nice 300CD, '82 model, under 200K miles. I think he wants 5,000 bananas. I'd like to have it myself, but I got mercedes all over the garage at the moment.