Cleary brought concerns of teams manipulating the set-restart rule to the fore last month when he accused Newcastle of making it part of their game plan.

The comments sparked a war of words between Cleary and Knights coach Adam O'Brien at the time, after Newcastle gave away five restarts on the first tackle against the Panthers.

They have prompted a flow-on effect.

Figures show that more than 60 per cent of set restarts have been given away on the first two tackles this year, with teams using slow play-the-balls to set their defensive line.

The theory is that there is minimal punishment for the act, given teams can remain boxed into their own end rather than earn a piggy-back penalty.

In response the NRL on Thursday reminded referees to penalise whenever they felt the ruck infringements were deliberate, particularly early in the set.

Referees were also encouraged to use the sin bin when appropriate.

"I think they're onto it," Cleary said.

"The rules were sort of thrust on the refs without their knowledge. It's hard for those guys, they are just doing their best.

"The players and coaches adjust throughout the year and try and use them to their advantage, that's what the game is about.

"The referees have to understand what they see as tactical and what they don't, and they've got the avenues to rule on that as required."

Penrith are one of the teams to benefit most from the quicker game.

The debate has sparked calls for penalties to be automatically given early in sets, or when teams are within their own 20-metre zone.

Another option floated on Thursday was that teams could immediately kick for touch on the restart being awarded, giving them possession if they find it.

While those ideas would take subjectivity out of the rule and make it a hard-and-fast law for referees rather than determining intent, Cleary doesn't believe that is required.

"The best referees are the ones who can understand interpretations and what's happening on the field, rather than just work straight off a rule book," he said.

"As far as I understand there is still that ability to be able to referee like that."

Australian Associated Press