How many hours per day does an average 3d modeller work (for a company)?

Well, if you are a freelancer you can pick your time. Otherwise you may need to get special glasses from computer screen or just simply lower your brightness on your screen.

about 24.... cause we think about it when we dream... but seriously, expect some 4 hour days and lots of 12 and 15 hour days.. especially near milestones and crunch-time

You need some blue light protection if your eyes get tired. Look for screen protection glasses or softwares for that.

As DerrickMoore said, often 10 to 15 hour days. Some days, only a few hours. Freelancing is no better. In fact, now that I'm freelancing, the extended days can be about 20 hours. That is, often people seem to hire freelancers when it is way too late to solve a problem they're experiencing. Architects and ad folks, especially........

It does sound like you should visit an optometrist and get your eyes checked. Plus, look into things that might make for a healthy lifestyle. I routinely put in 8-10 hour days, but I try to spend a bunch of time in the gym, as well. Regular exercise and workouts are essential.

You can look into some solutions here.
https://www.techrepublic.com/blog/five-apps/five-free-apps-to-help-remind-you-to-take-a-break/
https://www.howtogeek.com/322433/four-simple-timers-that-remind-you-to-take-breaks-from-your-computer/

我也差不多

The same

It depends if you are a freelancer and make your own hours, or if you work at a company so you have to do the hours you agreed when you got hired.

People over estimate how much they do the actual work. This jas been studied widely. I'm freelancer and entrepreneur in 3D visualization field and I work on average 3-6 hours a day when I have some work to do. Sometimes when I'm in the rush I sleep in my office and do nothing but model (maximum number of hours spend 3D modeling here is about 10h). When I'm creating 3D assets or doing something that is not related to client work, I model 1-3h on average.

Working with 3D art is seasonal for me, sometimes I do it more, sometimes less.

I track every minute every day how much I work so my numbers are true working hours, which not include scrolling sosial media or eating lunch etc.

Someone might do more work but optimal time spend modeling is between 4-5h a day.

If someone tells he is working 12-16h every day, I don't buy it.

Hope this helps!

If only, .........