I'm in the process of starting an airline ... (nothing special, actually just a small GA operation), however AC commanders will ALWAYS be encouraged to err on the side of safety. For us it will be the cashflow cost of an uplift (rather than the fuel/mass penalty) that will be the greatest problem ....
However ......
Departure delay after start-up (common for GA types at Intl airports) followed by stronger headwinds than forecast, followed by a hold at destination, followed by a weather go-around, followed by further holding, coupled with fuel guage/totaliser error, followed by a serene silence on the next app, followed by an impact between AC and small planet ..... End of my business.
Therefore .......
Dont skimp on the fuel.
OK, so a small GA operation will not have the same commercial considerations as the big guys, and nor will the fuel planning have such an impact on the bottom line.
But .......
I question if my operation would have the same corporate attitude to fuel uplift if I were not a pilot. I think not!!!