We call it Command training!
However we went through years as a S/O and F/O in the system and it becomes the norm.
I presume at REX the F/Os do take-offs and landings??
The Captain already supervises these, just let the F/O do the flight planning, order fuel, liaise with other staff and make operational decisions [under his/her supervision] and this is ICUS. The Captain still boss, and if WX or X-wind not OK then Capt's sector. F/Os log co-pilot when Capt's landing and ICUS when it's theirs.
This ICUS goes towards ATPL hours for eventual Command.
Regards,
Tank