Police say their hopes of finding Ms Wallace alive are diminishing and stress there are no suspects in her disappearance.
The 47-year-old was reported missing on the morning of November 30 after becoming separated from her partner at the Federal Falls trail on Mount Canobolas, 20 km outside Orange.
The pair arrived at the popular walking track and camping spot in the early hours before sunrise.
Police Rescue crews and State Emergency Service volunteers have been searching through thick scrub and rocky bushland for any trace of Ms Wallace, who was last seen wearing an orange jacket, black pants and sandals.
Central West Police District commander, Assistant Superintendent Gerard Lawson, said police would continue looking for Ms Wallace over the weekend, after a white crochet garment was found on Thursday.
Other pieces of clothing were discovered about a week ago, though investigators are unable to link them to Ms Wallace until DNA results are returned.
"Finding those garments now gives us an area to focus our attention," Mr Lawson said on Friday.
"For the sake of the family, it's important to try and get them some answers and try to find her."
He said Ms Wallace's partner is not a suspect and is providing information to police.
"I would caution the community about speculating on what they think might have happened. At the moment, for us, it's an open question.
"We've got an open mind to all possibilities, but we certainly don't believe at this stage it looks like a homicide."
The investigation has been able to address some of the more "bizarre" aspects of Ms Wallace's disappearance, Mr Lawson said, but he declined to give further details.
Temperatures on Mount Canobolas have fallen below zero this week, with some days of strong, cold winds and rain.
"The tragic reality is that day by day, the chances of finding her alive are diminishing, but we still hold hope and we're still in contact with the family," Mr Lawson said.
"We'll only know when we find her."
Police considered the concerns of Ms Wallace's son, Tyrone Stewart, who told The Central Western Daily newspaper it was unlike her to go bushwalking to look at the sunrise.
"We factor it in when we make decisions ... about where we should search and about the behaviour of lost persons," Mr Lawson said.
"It's a whole breed of science about the psyche and the intent of people that go missing."
Specialist search dogs will be brought to the mountain early next week to help the police operation.
Police Rescue officers walked the Federal Falls trail on Friday morning, taking a steep path that leads to a fast-running waterfall.
Mr Lawson said it was unlikely Ms Wallace had made her way off the mountain, but continued to ask the community for help.
Anyone with any information is urged to call Crime Stoppers on 1800 333 000.
