Actually, the 6-hour thing is a little more involved:
JAR-OPS 1.295:
(c) An operator must select at least one destination alternate for each IFR flight unless:
(1) Both:
(i) The duration of the planned flight from take-off to landing does not exceed 6 hours;
and
(ii) Two separate runways are available and useable at the destination and the appropriate weather reports or forecasts for the destination aerodrome, or any combination thereof, indicate that for the period from one hour before until one hour after the expected time of arrival at destination, the ceiling will be at least
2 000 ft or circling height + 500 ft, whichever is greater, and the visibility will be at least 5 km. (see IEM OPS 1.295(c)(1)(ii));
or (2) The destination is isolated and no adequate destination alternate exists.
So its not just a case of destination being less than 6 hours away..... hopefully the full context of the JAR-OPS paragraph will help clarify the proper intent.