Ideal amount of time is as long as it takes for a meaningful task to be completed. That’s the natural way.

Hundreds of years ago, people used to work for as long as necessary to finish a project - the artisan approach.

Then the industrial revolution spoiled all that by creating a time-based approach to work, which suits the mechanized form of work that was required.

I’m self-employed and I don’t have a fixed time schedule - though I’m very organized (if you know what I mean).