Rondae Hollis-Jefferson took one shot after another — grunting occasionally when the ball hit the rim and bounced off — and didn’t stop until the only people left on the court were him and two coaches. For an hour after practice ended Friday, he tried to hone the jump shot that could be the key to expanding his game.

He took too many to count, and that’s the way he needs it to be.

“Never count,” he said at the Nets’ training facility, drenched in sweat and out of breath. “I let the coaches count. I just shoot. I look at it like if it feels good, then it was a good shot, and try to keep it the same way.”

The key to his progression is making that jumper a quick, fluid motion and being “shot-ready,” he said. Mechanically, it means working on an early release while developing consistency. Psychologically, it means trusting in the shot that failed him fairly regularly in his injury-shortened rookie year: He shot 28.6 percent from three-point range and 38.9 percent on all jumpers in 29 games last season.

He tinkered with his shot a lot throughout high school and college. “I tried to change it too much, and it’s probably like in my brain, ‘you shoot too many different ways,’ ” Hollis-Jefferson said. “It’s still lingering a little bit, but it’s working its way out — on the base floor going to the basement.”

It’s something Jeremy Lin said he struggled with all of last season when he too was in a transition phase. It’s not easy to vanquish years of muscle memory, and the change in his jump shot — Lin isn’t jumping as high or bringing the ball back as far — initially caused a dip in his numbers. After almost a year and a half (he started working on it after his final season with the Lakers), it clicked.

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“There were times . . . I would revert to my old shot, then I’d go to my new shot, then I’d be somewhere in between,” Lin said. “After the game, I would just be like, ‘Man, I don’t even know what form I’m using right now.’ . . . the other one was too hard on my legs, and when I had fresh legs, I’d shoot it well, and when I didn’t, I wouldn’t . . .

“Changing my shot, it’s much more repeatable . . . It’s less contingent on how much energy I have.”

Hollis-Jefferson and coach Kenny Atkinson are looking for equally positive results. He’ll likely always be a defense-oriented slasher, and the Nets have no intention of stripping that from him, but they recognize the need to expand his repertoire to survive and thrive in a league that has gone through a significant transformation of its own in the past decade.

“We have a plan and a unified plan so that he doesn’t hear 28 different things,” Atkinson said. “I call it the curse of the great athlete. They’re so used to driving it all of the time and going to the offensive boards, they could always just drive by people . . . In today’s NBA, [a strong jump shot] is a quasi-necessity. He’s going to have to keep them honest.”