I start off a mini nuc with a virgin queen but once she has mated and it has brood you want easy access to insert a queen cell after removal of the queen. In an ideal world I remove a mated queen and put a ripe queen cell straight in. 'Mating in Miniature' is an interesting read but is pretty dated stuff and recommends starting fresh each time. There is a big focus on a single frame mating nuc with glass sides.
If you set up mini nucs for continuous production you can get 3 or occasionally 4 queens in a season - weather permitting. Overall I would average somewhere between 2 and 3 mated queens per unit.