This is what I recently saw quoted about Individual Flight scheme and its potential effect at a tropical destination with wet and dry seasons: "European authorities allow ‘mature operators’ an individual fuel scheme (IFS) for CONT fuel, based on statistical data (older data usually carrying lower significance). Especially after a long period of nice weather, (minimum) CONT fuel of 5 minutes (!) is not unusual, even on 13 hour flights. In Europe you can therefore see CONT fuel increasing for instance over the winter period (as weather deteriorates and delays are more frequent). Same at the start of the TS season: likely low CONT fuel figures."
I think what is being said is that after a long period of good weather(due to the good weather season), the season changes and the poor weather arrives but the flights at the beginning of the season with poor weather are flying with reduced fuel due to the past few months affecting the fuel calculations in a negative ways at the beginning of the poor weather season.
My old company had a couple of situations of 5 or so go-arounds with a couple of captains determined to get into non-precision approach, uncontrolled airports in poor weather but with lots of gas on board. One was a medium sized jet. 15 or more years ago now.