O'Connor was even able to make room for an extra 50 late entries from Carlton School, for example.
Taking part for just the second time in the older Year 7-8 boys race was Blair Gowen of Westmere School, who would finish second to Wanganui Intermediate's Flynn Johnston when the finishing times of the three staggered-start races were confirmed.
"It's a little bit easier," said Gowen.
"The best part definitely is the slide up there [on hillside]. That's cool.
"The toughest part is going back there [up the hill]."
Not having any problem with the jumps, pits and fire hoses was "Ms Tough Kid" Jessica Johnstone, of St George's School.
Johnstone got out to an early lead in the Year 7-8 girls race and was never headed, building up a big lead as she climbed the hill and then came back down to get under the final net and slide welcomely down the last obstacle.
It was Johnstone's fifth consecutive individual win at the Tough Kid challenge, starting as a Year 3-4 entrant in 2012.
"It's my thing. This is what I love," she said.
A veteran of the course, Johnstone had learnt how to pace herself and control her breathing over each section.
"It's getting easier, to be honest."
She kept it up as part of St George's win in the Year 7-8 team race later in the afternoon.
However, when collective points were added up, it was Wanganui Intermediate who retained its Toughest School (Senior) title, being helped by several Top 3 placings in the Year 7-8 events.
Also keeping an amazing hot streak going were St John's Hill School - with Ben Karatau, Trista Ormsby and Chase Morpeth all winning their individual races, while the school won both the Year 3-4 and Year 5-6 team grades.
It allowed St John's to hang on to the Toughest School (Junior) title for a sixth consecutive year.
Results
Year 3-4 Boys: 1. Ben Karatau (St John's Hill School); 2. Karn Hatfull (Kaitoke School); 3. Luca Sheridan (St John's Hill School).
Year 3-4 Girls: 1. Trista Ormsby (St John's Hill School); 2. Lucy Wilkinson-Smith (St John's Hill School); 3. Emily Coreoran (Westmere School).
Year 5-6 Boys: 1. Chase Morpeth (St John's Hill School); 2. Oliver Jones (St George's School); 3. Tawai Pinnock (Churton School).
Year 5-6 Girls: 1. Lillah Cornellius (Churton School); 2. Estelle Murray (Westmere School); 3. Carrie Renney (Castlecliff School).
Year 7-8 Boys: 1. Flynn Johnston (Wanganui Intermediate School); 2. Blair Gowen (Westmere School); 3. Jonty Tripe (Wanganui Intermediate School).
Year 7-8 Girls: 1. Jessica Johnstone (St George's School); 2. Ella Thompson (Te Wainui a Rua); 3. Maggie Jones (Wanganui Intermediate School).
Year 3-4 Teams: 1. St John's Hill School; 2. Mosston School; 3. St George's School.
Year 5-6 Teams: 1. St John's Hill School; 2. St George's School; 3. Whanganui East School.
Year 7-8 Teams: 1. St George's School; 2. Wanganui Intermediate School; 3. Westmere School.
2016 Toughest School Junior: 1. St John's Hill School; 2. Westmere School; 3. St George's School.
2016 Toughest School Senior: 1. Wanganui Intermediate School; 2. St George's School; 3. Westmere School.