{"id":66842,"date":"2026-08-31T08:00:33","date_gmt":"2026-08-30T23:00:33","guid":{"rendered":"https:\/\/norimen.net\/?p=66842"},"modified":"2026-08-29T21:29:18","modified_gmt":"2026-08-29T12:29:18","slug":"overtime-diminishing-marginal-utility-model","status":"publish","type":"post","link":"https:\/\/norimen.net\/en\/overtime-diminishing-marginal-utility-construction\/","title":{"rendered":"\"The More Overtime You Work, the More Money You Make\" Is a Myth | \"Overtime\" on Construction Sites Through the Lens of the Law of Diminishing Marginal Utility"},"content":{"rendered":"

Hello, everyone.<\/p>\n

This is Enta.<\/p>\n

I went to the dentist the other day, and my tooth got swollen and my face swelled up...<\/p>\n

After they removed part of the cavity and put in a filling, it seems it got infected...<\/p>\n

Take good care of your teeth!<\/p>\n

\n

But that's beside the point.<\/p>\n

In economics, there is a concept known as the \u201claw of diminishing marginal utility.\u201d<\/p>\n

Simply put, this law states that for every additional unit of a given good consumed, the satisfaction (utility) derived from it gradually decreases.<\/p>\n

The first beer tastes absolutely amazing, but by the fifth one, it\u2019s not that impressive anymore lol. You know how it is.<\/p>\n

Even if I bought a new iPhone 17 and then bought an iPhone 18 the following year, I\u2019d probably just be like, \u201cHmm, so that\u2019s it?\u201d<\/p>\n

I thought this might apply directly to overtime work on-site as well, so I decided to look into it a bit.<\/p>\n

The first hour of overtime is different from the fifth hour in terms of value<\/h2>\n

I worked from the morning, finished at the end of my shift, and then worked another hour.<\/p>\n

During that first hour of overtime, since I\u2019m still in the flow and my mind and body are still working, I\u2019m able to get a decent amount of work done.<\/p>\n

However, as the second and third periods pile up, the amount of work that comes out of each hour gradually decreases.<\/p>\n

Fatigue builds up, concentration wanes, and mistakes increase, leading to rework.<\/p>\n

As a result, if you ask, \u201cDid the work actually progress by the exact amount of time we extended it?\u201d\u2014well, that\u2019s not how it works.<\/p>\n

This is precisely the phenomenon of diminishing marginal utility\u2014the phenomenon in which the value (productivity) derived from an additional hour (one marginal unit) decreases as time goes on.<\/p>\n

\"Slope<\/p>\n

In fact, research indicates that \u201c50 hours a week\u201d is generally considered the threshold.<\/h2>\n

Since my personal impressions alone aren't very convincing, I found various references on this topic in labor economics materials. (All sourced from the internet.)<\/p>\n

According to data published by the Japan Institute for Labor Policy and Training (JILPT) in 2017,<\/p>\n

As part of a study using data from overseas factories, a report has been cited indicating that marginal productivity declines significantly when weekly working hours exceed 50 hours.<\/p>\n

Another study also appears to report that a 10 percent increase in overtime work leads to a 2 to 4 percent decline in marginal productivity.<\/p>\n

In other words, the idea that \u201cthe more overtime you work, the more work you get done\u201d no longer holds true once you exceed a certain amount of time.<\/p>\n

This means that just because someone who can complete 100 tasks in 8 hours works for 12 hours doesn't mean they'll end up completing 150 tasks.<\/p>\n

In fact, it means that, overall, the results can even end up being negative due to fatigue and mistakes.<\/p>\n

In my case, when I'm tired, I end up mindlessly fiddling with my phone or browsing the web for other things, and I get distracted...<\/p>\n

\"The<\/p>\n

Starting in 2024, the construction industry will no longer have \u201cunlimited overtime.\u201d<\/h2>\n

Starting in April 2024, the construction industry became subject to limits on overtime work.<\/p>\n

This is what\u2019s known as the \u201c2024 Problem\u201d in the construction industry.<\/p>\n

According to the Ministry of Health, Labor and Welfare\u2019s guidelines, overtime work is generally limited to 45 hours per month and 360 hours per year; even if a \u201c36 Agreement\u201d with special provisions is concluded, the annual limit is set at 720 hours.<\/p>\n

Precisely because this is an industry where delays in construction schedules and changes to work plans due to weather are a daily occurrence, it had become almost a given that overtime would be used to make up for them\u2014but that very assumption has now been overturned by law.<\/p>\n

\"Confirming<\/p>\n

So the only options are to \"hire more people\" and \"fine-tune the process.\"<\/h2>\n

The law of diminishing marginal utility teaches us a simple fact: \"Even if you keep adding more of the same resource, you will eventually reach a plateau.\"<\/p>\n

If overtime\u2014as a resource\u2014has reached its limit, we have no choice but to switch to another resource.<\/p>\n

Bring in one additional support person; extend the morning planning meeting by just 5 minutes; decide the order of material delivery the day before.<\/p>\n

This means that at this stage, the \u201ceffect per additional unit\u201d is still greater here.<\/p>\n

Well, that's assuming there are people around, of course.<\/p>\n

Before extending the time, it\u2019s a good habit to pause and ask yourself, \u201cIs that hour really worth it?\u201d<\/p>\n

I believe it\u2019s something everyone should have\u2014whether they\u2019re the overall manager, a foreman, a site supervisor, or just a member of the crew.<\/p>\n

It's also important to go home early to recharge and get ready for tomorrow, rather than wasting time working overtime for no reason!<\/p>\n

On the other hand, I won\u2019t deny that Japanese people also like this approach to work\u2014wrapping things up neatly\u2014but it\u2019s best to do so in moderation.<\/p>\n

When it comes to working abroad, there are a lot of countries where people don\u2019t bother wrapping things up neatly\u2014they just drop everything the moment their shift ends and head straight home, lol.<\/p>\n

 <\/p>\n

See you later.<\/p>\n

There are limits to how much you can boost productivity and generate profits without working overtime!<\/a><\/p><\/blockquote>\n