Hmmm, I'm not too comfortable with entering an artificially higher fuel than actual, it's much too easily forgotten. Our company recently had a crew who entered the expected landing fuel to calculate Vref (Boeing procedure) and didn't realise why they were getting an INSUFFICIENT FUEL MESSAGE.
What I do is to initially enter the Mean Wind (available on the CFP) for the entire flight, after entering that the time and fuel at destination are quite reasonable (good for the passengers in-flight display also).
After that, enter the entire route's segment by segment winds, but leave them un-executed until the entire set is entered, then execute them. The problem is that for a very long flight, this might take 15 minutes or so to do it properly, and inevitabely other information is needed from the FMC in that time, and the work done so far executed to save it....... and along comes the INSUFFICIENT FUEL MESSAGE again.
Life wasn't meant to be easy! (With thanks to Malcolm Fraser).
Regards,
Old Smokey