"Leading up to coronavirus there was very slow progress," he said.
"This was specifically to reduce some of the risks around nursing staff being overworked in DHBs."
Only Northland DHB has 100 per cent implemented Care Capacity Demand Management (CCDM) by the cut-off - and five were close at more than 90 per cent.
Canterbury DHB was at 49 per cent and Waikato at 34 per cent.
In his response to Reti's written Parliamentary question on the issue, Health Minister Andrew Little's office said Canterbury and Waikato were late adopters of the capacity management programme.
The Waikato DHB's roll-out was then further delayed by the cyberattack last year.
Reti said now is not the time for expensive reforms of the health sector.
"When the sector is already struggling for workforce, struggling to keep up with demand - even before whatever Omicron may bring towards us - this is a terrible time to be restructuring the sector."
A Government spokesperson said Little has made it clear he expects all DHBs continue to implement CCDM.
"While many have made good progress to implement it, several are behind for a variety of reasons, and the ministry is working with them to ensure CCDM is implemented as soon as practical," they said.
As of September, Waikato has increased its progress to 42 per cent and the acuity tool as part of the programme is being used to share staff across wards.
The board said it had aimed to have the programme fully implemented by next month, but this has now been delayed becasue of Covid.
Staffing continued to be an issue, but numbers had increased in some wards and emergency department, it said.
Canterbury's midwifery and maternity services executive director and acting nursing executive director, Norma Campbell, said the DHB was closer to meeting the 100 per cent target.
National shortages of nurses and midwives have been compounded by the border closures.
"This means we have to adapt and flex resources to meet demand, with some staff regularly picking up additional shifts," Campbell said.
"We have an active recruitment programme under way for these vacancies including talent sourcing from overseas, multi-channel advertising across all job boards, targeted campaigns, recruitment open days and attendance at Career Expos."
The next report is due this month.