Star Penrith signing Trent Merrin has turned his nose at the NRL’s new shot clock rules, labelling the changes as the latest gimmick to come out of league central that you “can’t really buy” into.

The Penrith-Parramatta trial was the only game of the weekend to involve the countdown for both scrums and line dropouts, as well as the highly-anticipated referee bunker.

And while both Panthers coach Anthony Griffin and Eels counterpart Brad Arthur were happy with the initial results, an honest Merrin took aim at the NRL for continuing to tinker with the rules.

“They keep changing rules every year so you can’t really get used to something,” he said.

“It’s been efficient for us because you’re getting more time (to rest), I think. But they’re going to play around with the rules every year.

“Things are going to come in, and things are going to come out. You can’t really buy into it.”

In a bid to reduce time wasting and to increase fatigue, the NRL has introduced a raft of changes for the 2016 season, including the reduction of interchanges from 10 to eight.

A 35-second shot clock on scrums has also been brought in, designed to lower the previous average of 40 seconds per scrum.

The early feedback from players and coaches throughout the trials is that teams are tracking to scrums quicker but are then found standing around waiting for time to expire.

“What do they do – make it 25 or 20?” Griffin said. “I didn’t notice it at all, so I ain’t got an issue there. If one teams wants to get in there and pack it quick – they’ve got to pack it, don’t they?

“On a whole, I didn’t notice it much.”

Arthur was a fan of the changes.

“I didn’t notice (the bunker) as disruptive as I had my head in the game,” he said.

“We had the shot clock for Canberra in round 26 last year, and we’ve done a fair bit of training for it in the pre-season. I think the shot clock for the scrums and dropouts are good. I like that.”