Oil breather

How much, if any, oil should be blowing out of the crank case breather tube next to the oil filler cap? I know it's not a good idea, but I have been running it with no tube or filter, does the presence of such create some sort of back pressure to keep the oil where it belongs? I'm not gettign massive amounts of oil out of this, probably less than it looks, but I'm just wondering how much is too much. The engine seems to be running fine, no missing, lots of power, no smoking out of the tailpipe or anything. Thanks, Wes