There is some fallacious reasoning along the lines of "Bigger is always better".
Eating food makes you satisfied. Person A has eaten more food than Person B, therefore Person A will be "more satisfied" than Person B.
This could be fallacious because Person B's available food may be enough to completely satisfy her and any extra food (which is available to Person A) will be surplus and make no difference to their level of satisfaction.
Wearing shoes on hot coal stops your feet from getting burnt. Person A has more pairs of shoes than Person B, so Person A's feet will be less burnt than Person B.
In this case, as soon as someone has one pair of shoes, anything else (or surplus) has no effect.
What is the name of this logical fallacy?