Ah - I think your understanding of the way our CFP is put together is slightly wide of the mark. It starts from a calculation of the fuel required to fly the flight plan to arrive at the end of the landing run with zero fuel. At each waypoint en-route, a 'min fuel required' number is included, which allows us to calculate from the fuel on board what we are likely to arrive with.
So, when I say that the CFP allows 1 to 2 tonnes from TOD, that is the calculated minimum fuel required to fly the planned arrival. It makes no allowances for ATC restrictions unless they are known to the planners at the time, or for holding which is allowed for (to a degree) in our minimum overhead fuel requirement and our route reserve fuel - which is 5% only if no En Route Alternate is specified (very rare), otherwise it is the 15 minutes' fuel I referred to in an earlier post.
Scroggs