While bean counters do drive most of what happens in aviation, in 32 years no one has ever asked why I blocked in with more or less fuel than what the flight plan said. There are too many uncontrollable variables. The flight plan is prepared a couple hours before departure and things change. You may get a different runway than planned or there can be traffic on the ramp. My record is being number 87 for takeoff. By the time you get to your destination everything could have changed over 12 or more hours. Hong Kong used to have a standing NOTAM, if you're arriving during certain hours we're going to be busy. Put on more gas than flight plan miniums.
I Used to do ACMI flights and the customer wanted to know the fuel onboard when we came into the system and when we left to adjust payment. On the other hand, used to also do LogAir (US Air Force contract) and we'd always come into the system on fumes and and top off when we were done, no one cared.