That 25-50Kt a year is an extremely scaleable production rate as well with no additional capex once they're up and running.
On top of that is the upside in the grade - they'll mine the highest grade ground first:
25,000t @ 2oz/t = 50,000oz pa
50,000t @ 5oz/t = 250,000oz pa
100,000t @ 5oz/t = 500,000oz pa