No one, not even Tom Brady, is immune.

When he looked into triple coverage Tuesday in practice and decided to test the waters anyway, he paid for it. Patrick Chung hawked down his throw. It was a win for the defense, particularly a secondary that swallowed more than its share of criticism last season.

But as innocuous as it seemed, it was important for Brady.

“A lot of times you learn from your mistakes,” the Patriots quarterback said. “You have to make the mistakes to learn from them. You never know how tight a window is until you throw it and it’s too tight. So you try to force the ball in certain areas and you learn and say, ‘I can’t do that.’

“You install new plays and you run them over and over and you try to identify all the problems when they come up and make good decisions.

“We’re out here running a ton of plays every day, 75-80 plays every day and believe me, they’re not all perfect. There’s a lot of learning every day and a lot of the situational stuff that we do. All of it’s a good learning experience.”

If you’re Ryan Mallett, the mistakes may seem magnified. The backup quarterback is in his second season, but because he missed the first few days of camp last year waiting to sign his rookie contract, it’s his first training camp.

His progress can be seen in things from learning the playbook to making the throws, though he threw a pair of picks in the same practice Tuesday. Rookie safety Nate Ebner skied up to snag one of them, another notch for the secondary.

But when coach Bill Belichick looks at the play, he takes nothing away from whatever strides Mallett has made.

“I think Ryan’s improved significantly from last year,” Belichick said. “I try not to get into those expectations, because guys progress at different rates, but I think what you’re looking for is improvement.

“Just to see players go out there and perform, take instruction, coaching, film, individual technique work, whatever it is. Then, the next time they get a chance to perform, they get better and the mistakes are corrected.”

If there’s a time to make a mistake, it’s on the practice field. That’s a point Belichick made with Mallett, and it’s a something he has talked to Brady about time and again in their 13 years together.

“Every interception in practice or every play that doesn’t get made in practice isn’t necessarily a bad play,” Belichick said. “I think we can all learn from those plays provided that we do learn from it and apply it in a similar situation next time, particularly at the quarterback position.

“There’s some balls that you try to stick in there and you learn that you just can’t do that. Then there’s other times you learn that, ‘Yeah, I can.’ ”

Belichick preaches pushing the limits, building confidence, but at the same time setting realistic parameters. It’s something Brady pays as much attention to as any quarterback on the roster.

“Whether Ryan or Brian [Hoyer] is in there taking the snap,” Brady said, “I’m paying attention to see what I would do if I was in there and vice versa. That’s the only way to play football.

“You can’t hear and only concentrate when you’re in. You have to learn from every day on the field, every rep in practice, mentally and then physically, when you go out and do it, you have to go out and try to execute it the best way you can.”

In Brady’s case, even after throwing for a career-high 5,235 yards last season, there are always things to improve. The integral pieces of the receiving corps (tight ends Rob Gronkowski and Aaron Hernandez and go-to receiver Wes Welker) are still together. But after the organization added more weapons in the offseason (Jabar Gaffney, Donte’ Stallworth, and Brandon Lloyd, among others), the process of figuring out how to use them is still in its early stages.

In his two possessions in the exhibition opener against the Saints, Brady went 4 for 7. Both drives stalled out, and it ate at him to not get a sniff at the red zone.

“We’re all trying to go out there and score, so when we don’t, it’s frustrating for all of us,” Brady said. “Hopefully we learn from this stuff and we move forward and we come out here for this week of practice and try to eliminate mistakes.

“We’re always going to make mistakes, but you have to be mentally tough enough to move on from those mistakes as well. That’s what we’re trying to do out here with these practices.