My job tends to ebb and flow, but can 100% say I’m not as productive when I go into the office.

I’d say a slow day can be as little as 2 hours while a busy day can be we’ll pass 8 hours.

Depends on what your personal definition of work is.

When I'm coding, focusing on just one deep problem, and the world around me is quiet, and I have food ready, and no one is bothering me, I might be able to do 6 hours at most. Afterwards, it starts to smell like fried brain.

When I'm coding light tasks, 3-4 hours, maybe 5 on a good day when I'm rested and content.

When I'm doing managerial tasks..... I've done 16 hours of continuous work, but it's "social" work, meaning no heavy logic problems, but rather relying on my personality and intuition to solve issues or juggle tasks for others.

It really depends. When I'm not taking my ADHD meds and if I don't have a project I'm passionate about, I would be lucky if I do an hour a day.

When I'm on my meds and if I have things I want to get done I can pretty easily put in 10 hours of true productivity.

I've been pure WFH since COVID though. I tried going in (I actually kinda missed the office) but I was way less productive there.