"The problem here is that deep drilling which is mostly DD and...

"The problem here is that deep drilling which is mostly DD and produces cores which are much more valuable to geos than rock samples run 24/7.
Running DD only in office hours will be much more expensive. Does Greater Fosterville DD drilling also have to be restricted to office hours?'

My amateur opinion ,
Yes DD goes deeper it will indicate stratified structure as is an actual core , guessing that is what you mean by DD being more valuable , RC will still show grade and other minerals present .
A niton type hand held tester can give instant results of pathfinder elements associated with gold ie arsenic , Are there pathfinder elements at Fosterville?
That would allow the company to drill consecutive holes with targeting based on instantaneous previous drill results
What is all the phrase "office hours" got to do with core and expense , the biggest variable on drilling would be the depth of drilling , drill shallow it is cheap , drill deep expensive , drill RC and tail with DD can be done to to reduce cost .