3. After that I take a decent break (e.g. an hour) because my productivity and efficiency reduce, and I'm not paid by the hour so a sustainable, high quality output that fits in with my life is the objective.

Not paid by the hour, but does this mean there is lots of overtime?

It's mostly based on profit, so it's all about balance. I usually average around 42 focussed hours per week, but if I did 84 hours per week we wouldn't make twice as much profit so I wouldn't get paid twice as much, which makes it kind of pointless. Obviously some weeks require more and that balances with some weeks that require less.

Where the marginal reward curve starts to rapidly drop is hard to gauge, but about three 3-hour blocks five days a week (with a shorter Friday) seems to be efficient and long term sustainable.

@joycestick I see, well you did a good thing following that 3 hour work then break. If progress is what is more important