Captains challenge is shit. Mostly used to challenge dumb 50/50 shit at insignificant moments. The vid ref is never gonna overrule the ref unless its dogs balls obvious. Its so useless no one has bothered manipulating it. Stopping the game to examine contentious knock-ons aint entertainment.
Best use of it was probably Glasby when he and his team were wrecked and needed a breather.
Should be used for points scoring decisions only such as check grounding, or if the ball just got over the cross bar for a field goal etc.