How long to you do deep work, and how frequently? Do you take breaks? What do you do during those breaks?

C Lia I.
I've personally found the pomodoro method works very well for me. 25 minutes on, 5 minutes off. Every fourth break is 15 minutes.
Anatol J.
I only do one 45 m session per day, because I usually don't need that much work done that requires intense focus. In an 8 hour day I work like a marathon, not a sprint. During the breaks I talk to people around me, or if I work from home, I relax in bed. The bed proximity does wonders for long term fatigue.
Rachel T.
Since I am self employed, I do deep work/ time blocking. Quite frequently.

I do time blocking the first thing when I wake up,after I meditate and before I get out of bed.
It looks somewhat like this.

Wake up 3:30
Meditate 3:45 or longer
After that i block out time for 30 minutes to write + edit for the coming day.

Next wash up
Then continue the day.

Other tips that help is getting ready by set cothes out the the night before .

I am getting better at this as I go with being self employed.

It is best to take your deep work seriously and breaks too.
I break ever 15 minutes with writing and drawing and games