must agree with LHR 777 as a CLC, it is pointless as a TRM in gving a sword or cirrus fuel of say 5000 and innsing a provisional based on this.
The number of years I have been dispatching and issued a provisional on system figures only to find the captain wants return fuel, extra fuel on CPH routes as the system fuel allows almost nil alternate and diversion so fugures end up being nearley 2T higher.
Also weather or long holds you may as well roll two dice to give you a fuel figure! Whatever you use almost certainally ends up being wrong!