The time cards Oakland city worker Kenny Lau turned in last year paint a stunning, if not improbable, picture of one man’s work ethic.

Lau, a civil engineer, often started his days at 10 a.m. and clocked out at 4 a.m., only to get back to work at 10 a.m. for another marathon day. He never took a sick day. He worked every weekend and took no vacation days.

He worked every holiday, including the most popular ones that shut down much of the nation’s businesses: 12 hours on Thanksgiving and eight hours on Christmas.

In fact, his time cards show he worked all 366 days of the leap year, at times putting in 90-plus-hour workweeks. He worked so much that he quadrupled his salary. His regular compensation and overtime pay — including benefits, $485,275 — made him the city’s highest-paid worker and the fourth-highest overtime earner of California public employees in 2016.

And, as incredible as it sounds, his bosses say he really did work all those days and hours. They describe Lau as a highly respected and dedicated worker in his field whose services are often demanded by developers looking to take advantage of Oakland’s booming economy and need for housing.

“Overtime is not required of any staff,” Gary Lim, Lau’s supervisor, said in an email. “It is Ken’s choice to work these hours.”

Lau and half a dozen other civil engineers work in the city’s Building Permit Center, where they scrutinize sheaves of plans for private developments ranging from the construction of high-rise luxury condos to the redevelopment of historic buildings. They check for compliance with local and state building codes and review surveys, site plans, grading plans, shoring plans, site improvements, historical features and energy compliance, Lim said.

Lim signed off on most of the time cards and approved Lau’s overtime in advance, according to the records. He did so apparently with little worry about the extra costs. The reason is simple: the Building Permit Center has an immense backlog of work — so much that developers who want their plans expedited can do so by paying the city engineer’s overtime. Thus, the city is compensated for those overtime costs.

Still, even developers’ requests for overtime jobs are backlogged.

Work efficiency experts say that round-the-clock tasks — like those seen in this case — raise troubling questions of oversight, workplace efficiency and resource allocation. And government accountability watchdogs say an auditor ought to examine cases of excessive overtime. One lawmaker told The Chronicle such high overtime pay to public employees erodes the public’s trust in their government.

“It’s important that the public have confidence in their public institutions and the use of their tax dollars. So when you have cases like this, whether it’s in Oakland or BART, it erodes the public confidence that’s so important to these institutions,” said state Sen. Steve Glazer, D-Orinda. “In this case, I don’t blame the employee as long as he’s correctly counting his hours. I do blame the supervisors and governing board for what appears to be an abuse of taxpayer dollars.”

The department’s workload is well known to top city officials. Assistant City Administrator Claudia Cappio said that Oakland hired three more plan-check engineers in recent months but that the demand for building permits outpaces what employees can approve on a weekly basis.

Cappio declined to discuss Lau’s overtime, instead releasing a statement, which read in part that city management “recognizes the heavy workload faced by our exceptional staff.”

“The reality is, Oakland has a multitude of development projects we need to get done,” said Councilman Noel Gallo. “And we’re understaffed in the development building.”

State Treasurer John Chiang, a gubernatorial candidate who created an online database of government employee salaries when he served as state controller, said that besides efficiency, cases of lengthy overtime raise questions for managers about the health of their workers.

Indeed, Lau’s co-workers agreed that stress is high in the department because of the work backlog.

At the second-floor office of the Building Permit Center at 250 Frank Ogawa Plaza, workers said they have been requesting a larger staff to handle the backlog for years.

Lau, who began working for Oakland in 1975, was in his office when The Chronicle showed up Friday afternoon but declined to speak with a reporter. He also did not respond to previous requests for interviews. His co-workers, who asked for anonymity, lauded Lau for his expertise, saying he knows the building codes backward and forward and can quote entire sections. He helps less senior engineers when they have questions, and is known to stay in the office until midnight, they said.

The Chronicle examined Lau’s 2016 time cards after Transparent California, a conservative think tank, spotlighted Lau in a recent report.

Although city officials and a representative for Lau’s union point to the work backlog in that office to defend the high overtime pay, his workload doesn’t appear to be anomalous or solely a product of the current building boom. He was regularly a top overtime earner as far back as 2002.

Robert Pozen, author of the book “Extreme Productivity,” said his research shows that in most organizations, the median hours worked per week is 45. But 10 to 15 percent of a typical workforce spends more than 65 hours at the office.

“Some of them are control freaks. They can’t delegate anything,” said Pozen, a senior lecturer at the Massachusetts Institute of Technology Sloan School of Management. “There are some people who take great pride in the hours they work and it’s a great part of their identity. And some people don’t want to go home.”

Pozen said his most important finding is that people clocking hours at the highest end of the spectrum tend to have ineffective and unproductive habits. Workers will “burn out if they have no chance to come up for breath,” he said.

At least one developer, John Protopappas, president of Madison Park Financial Corp., said that trend doesn’t seem to be the case with Lau.

“You can tell he’s working day and night because we’ll get emails from him at 3, 4 in the morning on weekends,” said Protopappas, who has been building in Oakland for four decades and regularly asks for his firm’s plans to be reviewed by Lau. “He’s got an incredible work ethic, and I hope he doesn’t retire.”

Even under the expedited process, in which developers pay for city plan checkers like Lau to work overtime, Protopappas said, it can take 16 months to get a permit. The city needs to hire more people to speed up the process, he said.

“Everyone wonders, ‘Why do we have a housing crisis?’ Part of it is because it takes so long to get a building permit,” Protopappas said. “Everyone’s trying to get their project done before the market cools off or there’s a recession or funding dries up.”

The Bay Area’s two largest cities have starkly different practices when it comes to building permit approvals and overtime — it either doesn’t exist or it’s rare.

Cheryl Wessling, spokeswoman for San Jose’s Department of Planning, Building and Code Enforcement, said no one doing building plan reviews can work overtime because they are all on salary. Bill Strawn, spokesman for San Francisco’s Department of Building Inspection, said overtime for people in those roles is rarely allowed because of the way the contract with the union was negotiated. In the few instances it’s authorized, the employees take compensatory time off instead of extra pay, he said.

State Sen. John Moorlach, a certified public accountant and former treasurer-tax collector for Orange County, questioned why Oakland doesn’t hire more workers.

“Managing manpower is not a difficult thing to do,” said Moorlach, R-Costa Mesa. “You look at the work and quantify it. If it well exceeds 40 hours per week per person, you have to hire someone else. Why would I pay someone at the top scale at time and a half when I can get an entry-level person to do the same work?

“This guy doesn’t have time to shower or shave or sleep,” he added. “The sad part of this is he’s had no time to enjoy the money. He’s got to have a monster bank account and no R&R.”

City budgeting sometimes makes it easier or less costly to allow overtime than to add staff, said Sylvia Allegretto of the UC Berkeley Institute for Research on Labor and Employment. The idea that government employees are overpaid compared with their private sector counterparts is a misconception, she added.

“When the population is growing and public sector workers are a smaller share of a larger population, you’re going to have some demand problems,” Allegretto said. “It’s really easy for people to think that public sector workers are the problem.”

Many areas of the public sector remain understaffed and underfunded compared with prerecession levels, she said.

There are still, however, concerns about the wisdom of working so much.

“I appreciate the dedication of our staff, but for anyone, regardless of your department, it’s not healthy to work so many hours,” said Councilman Abel Guillén. “After that amount of time, you can make mistakes and get hurt.”

Kimberly Veklerov is a San Francisco Chronicle staff writer. Email: kveklerov@sfchronicle.com Twitter: @kveklerov