The Dragons are the kings of the NRL's new captain's challenge and Brisbane rank last while all teams are getting better at using the video referral system.

It's taken a bit of time for clubs to settle on their captain's challenge strategies - at the start of the season several skippers were left red-faced after contesting on-field rulings which were blatantly never going to fly.

NRL.com Stats data also shows, after the first 14 rounds, Cronulla (15) had used the most challenges and Parramatta and Melbourne used the fewest (6). The Rabbitohs, Roosters, Raiders and Bulldogs had won the most with six apiece.

As a whole, sides are saving their video review until later in games - perhaps out of desperation or just because it's there - but most challenges are being won prior to the 50th minute.

When first implemented in round one the success rate was 25%. It's now 40% with an average of 12 reviews per round. Of the 169 total challenges, 67 (just under 40%) have been successful.

Sharks coach John Morris admitted his team had been guilty of some "howlers" but believes they've become more selective. He was surprised to learn Cronulla had used the most challenges.

"We didn't manage it well at the start. We were challenging everything and our strike rate wasn't very good, so we did need to discuss the process and how we go about that," Morris said.

"But we have had a couple of good ones. It's a crucial play. You need to make sure you're smart about it, not pull the trigger on it too early in the game if it's a 50-50 because you might need it later in the game.

"You want the captain to make the call and not anyone who just jumps up and says 'challenge it, challenge it'.

"The players also need to be empowered that if they genuinely feel it was the wrong call, they need to quickly get to Wade [Graham] and they've got that backing to make that call on-field."

Morris has been frustrated and delighted by the challenge system. He sought clarification after Penrith won a review against the Sharks in round nine despite taking "forever and a day" to make the call. There is a 10-second window to a lodge a challenge with the referee.

Cronulla successfully overturned a knock-on decision against the Titans last week that allowed them to stay on the attack.

"One of the rare ones," Morris laughed.

Things haven't quite gone to plan for the Dragons in 2020 but the Cameron McInnes-led outfit can lay claim to being the most savvy challengers having won five of seven reviews at 71.43%.

The Roosters (54.55% - six from 11), Eels (50% - three from six), Storm (50% - three from three) and Raiders (50% - six from 12) are the only other clubs to have got at least half their reviews right.

Although the Storm and Eels each botched a challenge in Thursday night's opening match of round 15 - Melbourne's one fell into the howler category with Brandon Smith knocking on at dummy-half after a Nelson Asofa-Solomona play-the-ball.

At the other end of the spectrum, the Broncos' 14.29% success rate (one from seven) is a reflection of their worst season in club history.

The Titans (23.08% - three from 13), Knights (27.27% - three from 11), Warriors (28.57% - four from 14) and Sharks (33.33% - five from 15) have been prone to burning their reviews as well.

A total of 35 of the 67 successful challenges (52.23%) have occurred up until the 50th minute mark of matches.

The most fruitful periods have been between 21-30 minutes (57% - 8 of 14), the first 10 minutes (56% - five of nine), 31-40 minutes (45% - 10 of 22) and 61-70 minutes (16 of 36 - 44%).

An overwhelming flurry of challenges have come in the final 19 minutes, accounting for 78 of the 168 overall challenges (46.43%) in regulation time. Only 30 of those have been successful.