They knew that the uptake over the entire month maybe 60-65% of the meals and could pinpoint days when they expected only 10-15% mainly duty staff, at weekends and grants. This gave them flex to manage the food on offer
In other words, an experienced Chef and/or Mess Manager. Who will expect to be paid comensurate with thier experience and skill.
Compared to a 17 year old burger flipper ......
Money, in the end. It's just down to money. Oh, and blind ignorance to drive something to it's illogical conclusion and the fear of loss of face when it goes predicatably t!ts.