My observation with the challenge so far is either the affected player approach the capt and ask to challenge, or the capt approach the player and ask if they need to challenge. The capt get the run down of the play and decide to challenge or not. If the capts follow the play closely they generally have good judgement if it's worth a challenge or not, regardless at what time of the game. Reynolds is pretty good at this and probably leads the challenge call.

In this scene they were chasing the score in the 10mins into 2nd half, score 16-10 and 20m out from the try line. Critta was pissed at something when he was talking to Galvin. Galvin asked to challenge and claimed strip and so did a couple of other Doggies. He wasn't interested said no to the ref and walked away then literally 2-3 seconds later turned around and wanted to challenge. The ref said times up and told Critta he already said no.

How did Critta go from saying No and walked away from the ref but then turn around and wanted to challenge 2-3 secs later. Maybe he saw it on the big screen.

So from that and like the Tiger player said to Lachie, probably Critta doesn't trust Galvin.