We are reminded every so often, all too often, that as much as the NFL trumpets its player safety advancements and tries to do the right thing, accidents will inevitably happen, mistakes are sometimes made, and players never stop being out of harm’s way.

The equipment isn’t perfect and ACLs aren’t made to be mangled and more than anything else the head isn’t made to be rattled, but the players know what they sign up for hoping that the risks are worth the rewards.

No one around the Giants is calling Sterling Shepard’s second concussion in less than a month career-threatening, but at the very least, it is a blow to the development of Daniel Jones and the 2019 Giants season and at the very worst, a haunting concern and potential trouble for a talented young receiver and relative newlywed and father.

NFL careers can end at any time, and because this is a different era, there will be fewer Wayne Chrebets, who needed the jersey ripped off him before he stopped playing and lived in darkness for years after he was forced to quit, and fewer Al Toons, and fewer Harry Carsons.

Shepard was evaluated for a concussion in the sideline tent by independent doctors and was sent back into the field of battle Sunday against the Vikings. He answered questions in the postgame locker room and didn’t seem out of sorts.

He showed up Monday morning and was placed back in the dreaded concussion protocol.

“He went back in the game and then he came in this morning and had some symptoms,” Pat Shurmur said, “which is not atypical of some of these concussions.”

The NFL and the NFLPA reviewed the procedures surrounding Shepard’s first concussion and they must do the same again now.

Shepard was promoted to No. 1 receiver and signed to a $41 million deal when Odell Beckham Jr. was traded. He is a feisty little gamer with terrific quickness and hands who developed an instant chemistry with Jones and appeared on his way to a career year.

“He’s a big-time playmaker for us until this point,” Jones said. “But we’re confident in the guys we got.”

What else can the poor kid say? The guys he’s got are headed now by Golden Tate, who had an underwhelming Giants debut following his four-game suspension.

Saquon Barkley is unlikely to play when the Giants face the Patriots on Thursday night, Wayne Gallman is out, Evan Engram is banged up, and now no Shepard.

Bring on Bill Belichick!

Bring on Tom Brady!

Bring on those Patriots!

“I don’t think we have a locker room full of fanboys,” Tate said.

Jones and the Giants are bigger underdogs — 16 points — against these Perfect Patriots than Eli Manning and the Super Bowl 42 Giants — 14 points — were against those Perfect Patriots.

“We’ve all played in big games, I think, at some point, and this is a big one because it’s the next one on our schedule. I don’t think we need to put too much pressure on ourselves. I think we need to keep our emotions in check.

“Enjoy having an opportunity to go play in a very hostile environment against a great team, and go out there and shock the world.”

The Giants have even less of a chance to shock the world without Shepard, arguably less of a chance than the Jets had to shock the world in Philadelphia without Sam Darnold.

The spleen, of course, is an entirely different matter, and Sam Darnold damn well better not be cleared by doctors if there is a shred of doubt whether he would be safe playing because his life would be at stake, especially behind the current Jets offensive line.

The spleen isn’t the body part the NFL has much experience monitoring.

But the head, and the evidence of CTE that has triggered suicides and abhorrent behavior in too many former NFL players, certainly is.

And so we should all keep our fingers crossed that Sterling Shepard’s head will not be in grave danger whenever he returns.