Serena Smith, a mother of four, and three other people were killed in a fiery head-on collision on SH2 near Te Karaka township near Gisborne on Saturday night.
Earlier that day pregnant 24-year-old Lesley Suddens died at the scene of a crash on State Highway 1 near Washdyke, north of Timaru.
On Friday night Annalese Bacon, 17, was killed at Reporoa in the Bay of Plenty.
In spite of constant reminders about the dangers of speed, alcohol and failure to wear seatbelts, those factors remained consistent in serious and fatal crashes, said Superintendent Griffiths.
"Families, friends, whanau all see these behaviours on a consistent basis and it's time we all started taking more responsibility," he said.
Inattention and fatigue were also contributing factors to road tragedies, he said.
This year there had been an increase in the number of passengers killed in car accidents, rising from 48 last year to 60 so far this year.
"The message we're trying to get out to the public is take responsibility for those around you. People don't just suddenly stop wearing seatbelts on Labour weekend. They do it all the time," he told Radio New Zealand.
"People need to step up and challenge it."
Changes to speed cameras came into force at Labour Weekend, allowing the cameras to identify trucks or other vehicles that are towing something and exceeding their 90km/h speed limit on the open road.
