When I was on 747s, we used to usually end up with round about 11k which is just over an hour to dry tanks. This would equate to about 2.3 on an NG, which is usually about CMR + 500 Contingency. About right, just over an hour to dry tanks. Landing with CMR is fine, Contingency is available to be used. There seems to be great horror amongst younger pilots if you ever start dipping into it. Flying back from the Far East and unable to get above FL260 for many hours because of overflying traffic, you can see your Contingency disappearing. You then have to restructure your fuel reserves in whatever way you can, and even end up losing your alternate altogether. But the younger guys really don't understand how it all works- when you can disregard your alternate. When I took minimum fuel recently, one of them came up with this: 'but if we use more than taxi fuel to get airborne, we HAVE to divert, don't we?'. I have to confess I looked at him and wondered whether to put him right, but I thought 'I really can't be bothered!'
As for shutting down with average figures of 2.7, this would be too much in a European operation. One must think of carrying 500kgs too much every flight, and what this costs over a year, and compare it with the cost of the diversions over a year if it were not carried. I would suggest no contest as there would probably be none. That 500kg statistically mostly merely delays a diversion that would happen anyway, so the justification for carrying it is not there.