That aside, only tailender Nathan Lyon (25) passed 20 as Australia failed to make more than 250 in a completed innings for the fourth time in five Tests.
But while Smith and Laubschagne are assured of their places in the Test side, several others do not have that luxury.
Cameron Bancroft, Usman Khawaja and Travis Head have all failed to finish the series, with selectors losing patience following a succession of low scores from the trio.
David Warner, an automatic pick since making his debut in 2011, has also endured a torrid time.
The 32-year-old has registered just one double digit score – the first Test opener in history to register less than 10 in nine innings of a series.
Bancroft was jettisoned after making 8, 7, 13 and 16 in the first two Tests but his replacement Harris has fared little better.
The Victorian left-hander has failed to reach 20 in five innings and is averaging just over nine.
The future of Khawaja, who was axed for the fourth Test to make way for Smith’s return, is also in doubt in what has been a stop-start international career since his debut in 2011.
Head, appointed vice-captain and highly regarded by coach Justin Langer, was left out at The Oval for Mitch Marsh after making just one 50.
It was a decision that was somewhat vindicated with the West Australian allrounder taking 5-46 with the ball, but Marsh only contributed 17 with the bat as Australia’s middle order failed to offer any meaningful support for Smith.
Matt Wade is Australia’s only other centurion besides Smith but his top score since making 110 in the second inning of the first Test is 34.
Second innings runs at The Oval could well prove to be vital currency going forward as Australia look towards the summer.
Smith admitted the batsmen’s failures are putting more pressure on the team’s impressive bowling attack who late on Friday found themselves bowling for the second time in the day.
“It’s always tough backing up, there’s no doubt about that when you’re a fast bowler,” Smith said.
“Us batters haven’t given them enough time rest unfortunately. But in Ashes cricket you have to keep digging deep.”