Yet the exhausting hours had a clear purpose.
The money went back into the community.
TIME reported that Darby's Walmart earnings helped students and their families pay for groceries, mortgage expenses and funeral costs.
His decision was also notable because Walmart was not actually his second responsibility.
Darby was simultaneously serving as principal of North Charleston High School and as a member of Charleston County Council.
The South Carolina House of Representatives, in an official resolution honoring Darby, described Walmart as his third job, taken on so that he could directly assist people experiencing financial hardship.
That detail adds another dimension to his story.
He was not a man with large amounts of unused time looking for a charitable project.
His schedule was already crowded with public-service responsibilities.
He deliberately created additional work for himself because he believed other people needed help.
"The Logical Next Thing for Me to Do"
Darby's explanation for his decision was strikingly straightforward.
He told TIME that he could not bring himself to turn away parents and students when he knew they were genuinely in need. Taking another job, he said, became the logical solution.
That philosophy helps explain why Darby did not initially view what he was doing as something extraordinary.
For him, the reasoning was simple.
There was a problem.
He had some ability to address it.
Therefore, he should act.
Before working at Walmart, Darby had already been dipping into his emergency savings to provide assistance.
But savings eventually run out.
A paycheck, by contrast, could provide a continuing stream of money.
Every overnight shift could become another grocery payment.
Another utility bill.
Another mortgage contribution.
Another small piece of stability for a family experiencing uncertainty.
The physical labor itself was not the point.
What mattered was what the paycheck could accomplish afterward.
The Story Was Supposed to Stay Quiet
Darby did not begin stocking Walmart shelves because he wanted publicity.
There was no social-media strategy behind it.
No campaign.
No plan to become a national news story.
The South Carolina Legislature later described the effort as something he had intended to champion quietly.
But quiet acts have a way of becoming visible, especially when a high school principal appears at a Walmart during an overnight shift.
Once people learned what Darby was doing and, more importantly, why he was doing it, the story began spreading.
Local news outlets reported on him.
National media followed.
Students learned that their principal was spending his nights stocking shelves.
The broader community discovered that his wages were going toward struggling families.
And what had begun as one man's private response to poverty gradually became a much larger effort.
WCSC, the CBS-affiliated television station serving Charleston, reported in January 2021 that Darby had taken the Walmart position specifically to help low-income students and families pay their bills.
Students interviewed by the station described him as deeply committed to the school and community.