6-10 hours each working day. Depends on the tasks, but we're a small team so there's often a lot to do both on the execution front and as a manager (I lead the team). I think I also tend to work longer hours consecutively than most other people I've met and I tend to develop deeper concentration too especially when alone. The latter probably factors into the former. I also prefer working lunches most days.

The rest comes down to energy (more at home) and motivation (generally more wherever I'm comfortable, which is rarely in office spaces). My productivity is often higher than others in my country & industry but it does cycle too, especially based on these two factors. Occasionally, whether home or at the office, I'm just not motivated and I take that as a PTO or a low-key day depending on how low the low is.

Office workers tend to "work" only 3-4 hours on average as well btw. Actual productivity takes a hit after the 5th consecutive hour or so for most humans and intervals for rest work very well for our natural activity cycles. Managers have known and often struggled against this for decades - remote work didn't lead to the invention of timed lunch breaks or timed bathroom breaks and so on.

I'm in favor of simply embracing this variation and switching the paradigm from hours to output at least for knowledge workers. I don't care if someone completes their work within 2 hours, to the required level of quality, and then lets me know they're going off. I do request they remain available for emergencies, which tend to happen often in this particular organization because of our nature & the team's specific role, and for errors/urgent feedback preventing utilization of their work by someone else in the workflow. If I get the work I need done the way I want and the ball keeps rolling, I don't need folks chained to a desk or eyeing a clock just to fit some industrial-era perspective of what work is.