The 39-year-old this week successfully helped seven of the eight who climbed with him to reach the 8848-metre peak despite atrocious conditions, including heavy snow and howling winds.
The climb cemented his place as one of Australia's greatest ever mountaineers and the nation's first to scale Everest three times.
It also followed his 2007 expedition when, under his leadership, 15 of 19 climbers made it to the top of the world, at the time the most successful Australian expedition ever.
Many climbing teams, even those regularly taking groups to Everest, fail to match such a strike rate.
According to 41-year-old Katie Sarah, who got close to the summit three years ago but returned for a successful attempt this year, Chessell's secret is no great mystery, just exhaustive planning, meticulous attention to detail and years of experience.
"Obviously it's a big mountain and so many things can go wrong, but his approach is always that you leave as little as possible to chance," Sarah told AAP in a call from the advanced base camp at about 6500m.
"He has the infrastructure to support everything, and everything that can be put in place to ensure the safety of the team is put in place."
Then there's Chessell's "enormously" high level of experience and knowledge of the mountain.
"There are so many fine details, but he's onto all of them," Sarah said.
Chessell also has such respect for Everest he will take only those who won't put themselves or other members of the team in danger.
Other groups have been criticised in the past for boasting that they could get almost anyone to the summit.
The exploits of Chessell and his team this year came as more than 250 climbers using the route from Nepal conquered the mountain in a little over four days.
Among them was Nepalese mountaineer Apa Sherpa, 50, who broke his own record by climbing Everest for the 20th time.
The figures did not include those climbing from Tibet, the route chosen by American 13-year-old Jordan Romero, who became the youngest person to scale Everest.
About 2900 people have now reached the summit since Sir Edmund Hillary and Tenzing Norgay became the first people to officially conquer the peak in 1953.
On this year's climb Chessell said the conditions were the worst he had encountered, by far.
"There was a fresh dump of snow and winds were howling. They were at least 30-40 knots on the summit and it was minus 26C, which is not great for humans at 8848m above sea level," he said.
"We almost called it off, but we all made it up and down safely."
On their way up the mountain Chessell's group was asked to help a Japanese climber who had reached the summit on Monday.
But by the time they reached him the man was dead.
"Also, another climber, I think from the US, or at least a US team, which was on the summit about the same time as us, died on descent and we were not able to help him," Chessell said.
The poor conditions on Everest also prevented Chessell from solving a mountaineering mystery surrounding the first climbers to reach the summit.
While Hillary and Tenzing are in the record books, some people think two English climbers beat them to the top by almost 30 years.
George Mallory and Andrew Irvine may have reached the summit in June 1924 but died on the way down.
The pair was last seen on the ascent, just a few hundred metres from their goal.
Mallory's body was found in 1999, but certain pieces of equipment, including cameras, and personal effects were not located.
Irvine's body has never been found.
Chessell thinks Irvine may have survived a fall, but died on his way down while taking a route not often used. He had hoped to find his body and the missing cameras during his descent on Tuesday.
"Unfortunately the huge dump of snow, which was not forecast and came completely out of nowhere, put a metre and a half of snow on top of everything," he said.
"I know it sounds strange, but at the time I couldn't help thinking that the mountain was acting to keep its mystery to itself."
