Tankering
Hog,
Every aircraft is different. The best way to work it out for your aircraft is to pick a trip which you have flown:
a. Note the fuel burn and time taken.
b. Work out what the Flight manual suggests you should have burnt.
c. Work out the difference as a percentage.
d. Work out the extra fuel burn from the FM if you had flown at max take off weight, i.e. full of fuel.
e. Apply the difference from c.
f. If the cost of the extra fuel burnt, at the departure airfiled prices, is less than the price difference at the destination then it is worth tankering.
I hope that is clear and helpful.
MM