Junior doctors are striking for the third time this month today, with 290 Blood Service laboratory workers also walking off the job this week.
Te Whatu Ora has accused the unions of knowingly scheduling the strikes at the same time to cause maximum disruption, saying the dual action will compound the impact on patients.
Hundreds of operations were postponed in last week's strike.
That included in the days leading up to the industrial action, to make sure there were fewer people in the ward that might be affected by the strike.
More surgeries were being deferred on Friday.
"We're trying to simplify these [junior doctor] agreements, make them more relevant" - Andrew Slater
Te Whatu Ora chief people officer Andrew Slater said there was concern both strikes were under way at the same time, causing a lot of disruption.
"But we've got plans in place that we need to have in place to safely deliver care."
There was an 18 percent pay offer on the table for the junior doctors and Te Whatu Ora had been in facilitation with the union, he said.
The facilitator was set to make a formal recommendation next week, he said.
The employment agreements for young doctors were very complex, he said.
"The offer on the table is between 3 and 29 to 30 percent with an average of 18 percent."
The blood lab workers started their industrial action on Wednesday by not working any extra hours, and are going on strike for four hours on Friday.
The PSA - which represented the lab workers - said the Blood Service and Te Whatu Ora were keeping a close eye on blood stocks and some staff would return to work if blood was needed for life-preserving reasons.
There was enough on hand for acute operations that could not be deferred, it said.
"The issue between our parties is about money" - Alexandra Ward
PSA union organiser Alexandra Ward said there was a 13 to 35 percent difference in the pay that a worker with the same experience doing the same work received at the New Zealand Blood Service, compared to if they worked for Te Whatu Ora.
Te Whatu Ora settled a pay equity claim with administrators two and a half years ago, she said.
"So for an administrator that works for the New Zealand Blood Service that means it's two and a half years, back since 1 January 2022, accepting lower pay.
"That's really hard to handle and we've been negotiating about this for seven months, people are struggling to pay their bills now."
It was not coordinated with the doctor's strike but "I think it should be a signal that things are not right in our health system when there are multiple groups of workers going on strike simultaneously," she said.
The four-hour strike was part of wider action that included not working extra hours and not processing AHF plasma, which was sent to Australia for commercial processing rather than directly to hospitals.
Next week the workers would strike for 24 hours if the dispute had not been resolved.
They want the Blood Service to pay them the same as their hospital counterparts, and plan to strike for longer next week.
The junior doctors are part of the Resident Doctors Association which represents about half of all junior doctors, more than 2500 of them.
President James Anderson said Te Whatu Ora has barely moved on its demands for fair pay and for an end to back-to-back 15 hour weekend shifts.
It was also trying to "claw back" a 50-year-old clause that meant doctors got $5000 when they passed their first exam, he said.
While the Employment Relations Authority had recommended halting the strikes at the beginning of facilitation, the union was sticking to its guns, he said.
"This glacial pace we've got going on at the moment is only happening because of our industrial action," he said.
"Toward the end of facilitated bargaining, the facilitator was no longer recommending we took strike action off the table, which we've interpreted as being recognition that strike action is the only thing that's progressing Te Whatu Ora forward."
The union also argued doctors should not be financially punished for wanting safer working conditions.
Te Whatu Ora chief people officer Andrew Slater said he was frustrated and disappointed the doctors were was still going ahead with the strike despite the Employment Relations Authority recommending they paused during facilitation.
The pay increase offer - between 3 and 29 percent - was fair, he said.
Hospitals would remain open and patients should turn up to appointment unless contacted, he said.
Wellington Hospital house officer and Resident Doctors Association delegate Kerry Appleton said Te Whatu Ora already paid doctors from another union more, because their contract did not include a safety clause which prevented doctors from working more than 10 days or four nights in a row. It now wanted to increase that pay gap.
"What was allowed prior to that schedule coming into existence [in 2016] was working seven nights in a row or working up to 12 days, so working your Monday-Friday, the weekend, and then another full Monday-Friday after that. That's a huge amount of work, that is incredibly fatiguing and ultimately, is not safe."
Appleton said increasing the pay disparity would force more doctors to choose between pay and safety.
Another junior doctor said patient wellbeing was a primary concern among the doctors. Eden Hawkins, who was among those on the picket line outside Wellington Hospital, said those she had spoken to were supportive of the strike action.
"When patients have brought it up with me on the wards or in other contexts there seems to be a really bolstering sense of support around us, which is really reassuring and heartening because there's obviously a conflict within ourselves when we strike, we don't want to be doing that."
Hawkins said ultimately the strikes would benefit patients - improving doctors' pay and conditions would help retain staff, therefore improving the standard of care.